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JBrowse FAQ

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Some frequently asked questions, and some hypothetical ones for fun

See the JBrowse_Configuration_Guide for more details



How do I get started with installing JBrowse?

To setup jbrowse on your server, the basic idea is to download the zip file, drop the files in a folder on a web server, and run the script.

You can do this for example by

  • downloading the zip file from, e.g.
  • unzip this file into your web server directory like /var/www/html or similar
  • make this directory "owned" by you e.g. `sudo chown -R myusername /var/www/html/jbrowse` (not strictly necessary)
  • cd into /var/www/html/jbrowse and run the script e.g. `./`

Then you should be ready to go. Note that as long as completes the "Installing Perl pre-requisites" phase of you should be good to go (the other steps are not strictly needed)

Now open up your website e.g. http://localhost/jbrowse and you'll already see that is is "setup" and you can see http://localhost/jbrowse/?data=sample_data/json/volvox has example data

Then you can simply run a small script to get your own genome loaded. For example, while you are in /var/www/html/jbrowse folder, then run

   bin/ --fasta your_genome.fa

This will create a folder named "data", and then visiting http://localhost/jbrowse/ will automatically load this "data" folder and youll see your genome.

Alternatively: you can try the JBrowse Docker container for a containerized deployment, or the JBrowse Desktop program to run without a web server (similar to IGV)

How do I load my genome as a FASTA file?

If you have JBrowse installed to your web folder and have run, then you can download a FASTA file for your genome and run

bin/ --fasta yourfile.fasta

This will setup a "data" subfolder inside your jbrowse subdirectory with your genome prepared to view. You can investigate data/trackList.json and other files in this "data" folder to see what it generated.

Then just open up "" and it should be visible with the reference sequence as a track. By default, visiting "" will read files from that generated "data" folder. Other configurations are possible, but this is the easiest one.

How do I setup a GFF track?

The most common feature track to use is a GFF file

Using is the easiest and most optimal way to load a GFF file for jbrowse

You can run

bin/ --gff myfile.gff --trackLabel trackLabel

Refresh your browser and your GFF file should be visible as a track. You may also experiment with adding --trackType CanvasFeatures, which is a newer track type that is more flexible to configure, or --type mRNA to only load mRNA features from the GFF, or other parameters that are listed in --help.

How do I set up a BAM file?

When you set up a BAM file in jbrowse, the best way to do it is as follows

  1. Put the BAM file and the BAM index (.bai) in your data directory (e.g. you downloaded jbrowse, and your did, which created a data subfolder. Put your BAM file in there)
  2. Then use like this: --label mybam --bam_url mybam.bam --in data/trackList.json
  3. This will only create a simple section of configuration in your data directory's trackList.json for the BAM file that will look like
        "storeClass" : "JBrowse/Store/SeqFeature/BAM",
        "urlTemplate" : "mybam.bam",
        "label" : "mybam",
        "type" : "JBrowse/View/Track/Alignments2",
        "key" : "mybam"

This basically just instructs JBrowse to fetch "mybam.bam" using the class that understands BAM data, "JBrowse/Store/SeqFeature/BAM", and display it with the "Alignments2" tracktype. If this does not work please post to github or

Other notes

  • Don't use, it is old and converting your probably humongous next-gen-sequencing BAM into text json is unwieldy
  • Your bam index should just be named the same as your BAM with .bai on the end
  • The does NOT copy the bam to your data directory for you, you put it there yourself, and specify the --bam_url appropriately
  • baiUrlTemplate is unnecessary if your bai file is just your bam file with .bai added onto the end, in that case it is found automatically

You can also add your config into a tracks.conf file instead of the trackList.json file, but you use a different format, for example


This is functionally equivalent to the trackList.json entry above

How do I set up a BigWig file?

When you set up a BigWig file in jbrowse, the best way to do it is as follows

  1. Put the BigWig file in your data directory and run, so if you have data/, run the command ` --label mybw --bam_url`
  2. This will update your trackList.json to have something like
       "storeClass" : "JBrowse/Store/SeqFeature/BigWig",
       "urlTemplate" : "",
       "label" : "mybw",
       "type" : "JBrowse/View/Track/Wiggle/Density",
       "key" : "mybw"

You could also add the --plot argument to to use the XYPlot version of the bigwig track.

Alternatively, you can manually add that snippet into trackList.json, or add this alternative track conf form into your tracks.conf file



  • It is discouraged to use bin/, it is a legacy script that converts a wiggle file into a series of pictures using libpng for viewing in jbrowse. The direct ability to access bigwig files is much better, faster, and does not require any file conversions
  • The urlTemplate is a path relative to your data directory, so if your file is in your data directory, it only needs to be the filename of the bigwig.

How do I set up a VCF file?

This is where the training wheels come off

There is no, so you have to edit trackList.json yourself

First bgzip and tabix your vcf file

    bgzip myfile.vcf
    tabix -p vcf myfile.vcf.gz

If your VCF isn't sorted for any reason, just use the GNU sort utility to sort it by chromosome and coordinate or get vcf-sort from vcftools

Now that your VCF is indexed, follow these steps

  1. Put the myfile.vcf.gz and myfile.vcf.gz.tbi in your data directory
  2. Edit data/trackList.json
  3. Put the following in there:
       "label": "mytrack",
       "urlTemplate": "myfile.vcf.gz",
       "storeClass": "JBrowse/Store/SeqFeature/VCFTabix", 
       "type": "CanvasVariants"

That isn't too bad right? All that does is automate that for your similarly for BAMs, so now that you have edited the config file by hand you are ready to take on the world!

Note you could also add your track to tracks.conf


Both of these configurations represent the same track.

How do I get IndexedFasta track to work in JBrowse

A short trackList.json with an IndexedFasta reference sequence track would look like this

   "tracks" : [
         "label" : "refseqs",
         "key": "Reference sequence",
         "storeClass" : "JBrowse/Store/SeqFeature/IndexedFasta",
         "urlTemplate" : "SOAPdenovo-genome.fa",
         "useAsRefSeqStore" : true,
         "type" : "Sequence"
   "refSeqs" : "SOAPdenovo-genome.fa.fai"

You can see from this that a couple things are needed

  • useAsRefSeqStore set to true
  • making label: refseqs is important when the storeClass is not the normal SequenceChunks class
  • the refSeqs attribute refers to the FASTA index file (normally it points to the refSeqs.json file)

With this setup, you do not need to have run on a FASTA file. Instead you can simply use the "samtools faidx" program to index your fasta file in a data directory, and set trackList.json up in this format.

General information

What webserver is needed for JBrowse

Most established HTTP servers such as Apache or nginx can work. You can just unpack JBrowse into your http web directory (/var/www/html, or htdocs, or similar) and follow the setup instructions

Other configuration about your server will depend on your needs, but generally no special setup is needed for the http server, and there is no "server side" code used by JBrowse (cgi, php, etc).

Note: servers like "SimpleHTTPServer" from Python or "http-server" from NPM are generally not full featured enough to run all JBrowse features correctly (SimpleHTTPServer does not support Range queries, and http-server interprets tabix files incorrectly). RangeHTTPServer does pass the test suite for jbrowse though, so it should work for tests (but not for compressed json files).

Also note: sometimes, people will download JBrowse and double click the html file and open up file:///c/myfolder/jbrowse/index.html in the webbrowser, however, running JBrowse like this is not recommended. This may appear to work for some limited cases but will fail on many others. You can use JBrowse Desktop if you want to use jbrowse locally without a webserver.

What is the difference between and

Ignoring version numbers here, the difference is that one is a "release" version and one is a "development" version. If you are going to be modifying source code of JBrowse's codebase, you probably want the development version.

The "release" version goes through a build step with minification so that loading the page takes less bandwidth. Different parts of the code go into different "layers", but the main layer that includes most JBrowse source code and JBrowse libraries goes into src/dojo/dojo.js

The "development" version does not go through minification, and so it is amenable to editing the source code. You can also use a github clone for developing source code modifications. See the next section for running from a github clone #How_do_I_run_the_code_using_the_github_clone

How do I run the code using the github clone

Running code off github is fairly straightforward, and you can actually run it on your webserver without any build steps

 git clone
 cd jbrowse
 bower install

Then move that directory into your web server root and you are ready to go.

Note: If you want to make your own custom build with minification (which reduces HTTP load on your users), you can install "cpanm Text::Markdown" and "cpanm DateTime" and then run the jbrowse Makefile

make -f build/Makefile release-notest

This purposefully excludes the perl test suite, but you can run those too with

make -f build/Makefile release

What are the different config file formats?

JBrowse uses both json and ".conf" files for configuration (the .conf is a custom format that is parsed on the client side), and both file types can contain the same types of information

Examples of JSON format

  • trackList.json
  • jbrowse_conf.json

Examples of conf format

  • tracks.conf
  • jbrowse.conf

If you wonder why you would use the .conf format, some benefits include: easy to edit, easy to append to with text file tools, can define multi-line functions (JSON doesn't allow newlines, so callbacks are specified on a single line).

All the config files are combined using a system of "includes" at runtime. The "order" behind loading all the config files is something like this:

  1. The index.html initializes a global Browser object, and the paramaters to the constructor are used as the start of the config
  2. The Browser class "includes"  both jbrowse_config.json and jbrowse.conf using defaultConfig
  3. The jbrowse.conf by default includes both {dataRoot}/trackList.json and {dataRoot}/tracks.conf, which resolves to whatever data directory is currently being used
  4. The trackList.json or tracks.conf files can themselves include other files, such as a "functions.conf" file

What type of coordinate system does JBrowse use

Internally it uses 0-based coordinates

When you view the data (like in the view details popups, and in their position on the browser) it is 1-based.

The functions like feature.get('start') would return 0-based.

What is the difference between CanvasFeatures and HTMLFeatures?

There are a lot of differences!

  • CanvasFeatures are newer.
  • CanvasFeatures can support Gene glyphs, i.e., a gene with multiple transcripts are grouped together on the screen. In HTMLFeatures, you have to load at the "transcript" level, so this loses the gene level info (if you do try to load the --type gene, it will just load "gene spans", but then it doesn't display the transcript subfeatures. not terrible, but not as cool as CanvasFeatures).
  • CanvasFeatures are faster if your have a lot of data.
  • They can support more dynamic shapes (See the SashimiPlot plugin for example of Arc track, or NeatCanvasFeatures for example of "intron hats")
  • They have different configuration functions. All the "style" methods on CanvasFeatures can be callback functions, so you can have a dynamic callback for the feature color, label, etc. The "glyph" can also be a callback, so you can make a function to change to a box or diamond glyph depending on feature attributes.
  • CanvasFeatures have better mouseovers. The HTMLFeatures mouseovers use the HTML title attribute which can only display plain text. On CanvasFeatures tracks, the mouseover it is a real tooltip that you can embed arbitrary HTML inside of.

What is a glyph?

Glyphs are a "unit" of drawing in a CanvasFeatures track. The glyph is just code that is responsible for drawing a feature on the screen.

What does do? will create a "search index" on, by default, the "names, IDs, and Alias" fields for tracks loaded with or It will not try to index ids from BAM files or bigwigs, but it does index names from VCF files too.

You can select specific tracks that you want to index with --tracks arguments to You can disable "autocomplete" by setting --completetionLimit 0 on You can "update" your search index by using --incremental

Also note: you can index additional fields of a GFF file with by specifying the --nameAttributes flag to E.g. --nameAttributes "my_custom_field,name,id". The default value for this flag is "name,alias,id". Note that the flag is passed to and then these values are automatically indexed by later.

What is the "label" in trackList.json and what is the key?

The track "label" is more like the track "identifier", it should be unique! The key is actually more like the name that is displayed for the track. It might sound counter intuitive to have label and key this way. Key is not a required attribute, but label is. The label can be specified by --trackLabel on command line tools. The key can be specified by --key.

How do I search for a feature in JBrowse

Some people don't know this, but the box that shows your current location, e.g. "chr10:1..1000 (1.0 Kb)" is also a search box! You can search for things that indexed here.

Also, the search index can be used to "link" to features, for example, if you construct a link such as http://localhost/jbrowse/?loc=GENE1234

Then the search index will resolve the location of that gene and jump to it automatically.

How do I get full text descriptions to be searched?

Try out jbrowse_elasticsearch, it is still experimental but it allows this. Or, implement your own JBrowse REST names API. The default is not built for searching full text descriptions.

How do I set up multiple genomes in a single jbrowse instance?

By default, the scripts will output to a subdirectory called "data" in the jbrowse folder

You can control that output with most scripts using the --out parameter. This enables you to have "multiple data directories".

Once the data directories are ready then use the URL bar to select which data directory to use with ?data=my_data_dir e.g.

Note that with Apollo, you can output the data directories to some given directory and add the directories via the user interface.

You can also setup the "dataset selector" see #What is the dataset selector and JBrowse_Configuration_Guide#Dataset_Selector

What is the dataset selector

The dataset selector is a dropdown that can list all the genomes that are in your jbrowse instance

To configure the dataset selector, set a dataset_id inside your trackList.json or tracks.conf on your data directory, and then in jbrowse.conf, add a list of all your datasets with the dataset_ids that you listed in the genome's data directory.


How do I change the name that is displayed on my features

If you don't like the names in the "Name" or "ID" column of your GFF, and you instead want to use some other field as the name to be displayed, then you can add this to your trackList.json

"style": {"label": "my_custom_field"}

Note: you can also index "my_custom_field" with too by supplying my_custom_field to the --nameAttributes argument from After loading it from in that manner, it will be indexed by

Also note: you can make the description a custom field too in a similar way

"style": {"description": "my_custom_description_field"}


How do I customize feature colors (with CanvasFeatures)

In CanvasFeatures, this is done with the style->color parameter. The style->color parameter can be a function, so for example, in trackList.json

    "style": {
       "color": "function(feature) { return 'red'; }"

Will make your features red

    "style": {
       "color": "red"

would do the same thing

It can be dynamic too though

    "style": {
       "color": "function(feature) { return feature.get('score')>50 ?'blue':'red'; }"

If you get a very complex function, consider putting it in a separate functions.conf file and include it, see config guide "Including external functions in trackList.json"

Note: with HTMLFeatures, it is similar, but you have to use hooks->modify instead of style->color.

Also note: you cannot create the functions via the UI in "Edit config". You have to specify the callback functions via the config files themselves.

How do I add a legend to the track in the "About this track" dialog?

You can add custom info to the "About this track" dialog boxes by specifying metadata for the track in trackList.json, e.g.

"metadata": {"legend": "Red means this, green means that"}

This will create a box called "legend" inside the "About this track" box.

All the "metadata" fields are added to the "About this track" dialog box, and it can also support HTML, e.g

"metadata": {"randominfo": "<p style='color:green'>Green text</p>", "otherrandominfo": "<p style='color:red'>Red text</p>"} 

You can also use the fmtDetailMeta and fmtFieldMeta callback functions to change pre-existing values

How do I customize the dialog boxes for the features?

There are many ways to do so.

  1. To customize the default 'View details' type popups, you can override fields by adding a function to your track config like fmtDetailValue_Name: "function(value, feature) { return value + ' is the original name'; }"
  2. To make a different custom action for a dialog, make onClick->action a javascript callback and make it popup your own custom dialog box, made using dijit or any other javascript type language. The function would have the format function(clickEvent) but you can access feature information from this.feature inside the callback
  3. Set action: "newWindow" and url: "{name}" can redirect to search google for the feature's name (note: the {name} is a template parameter that is automatically filled out when a feature is clicked)
  4. Set action: "iframeDialog" and url: "{name}"
  5. Set onClick->action to contentDialog and then set onClick->content to a string or a functioning returning a string or a "promise". A promise can come from calling dojo.xhrGet or similar so it can retrieve dynamic content. The function would have the parameters function(track, feature)

Those are just a couple examples

More straightforwardly, basically any field that exists for the feature (e.g. all the things in column 9 for a GFF) will be added to the default "View details" boxes, so it you add more details to the GFF3 column 9, then your popups will have more information.

How do I customize the main menu bar

Typically this is done using a plugin. You can make your plugin add new menu items. See the RegexSequenceSearch plugin for an example

You can also create a new "menu" i.e. (default says file, view, help) and you can extend it to use (file, view, tools, help) or similar. The GMOD/Apollo codebase does this

How do I customize the "track menu" on a track?

In general, you would want to make a new "track type", you can override _trackMenuOptions on your custom track type. See for example

How do I customize the right-click menus on features

You can edit the menuTemplate parameters on the trackList.json.

Note: when you add 1 method to menuTemplate, it overwrites 1 of the default elements in the default right-click menu. This is sort of a bug. If you want to "add" your method to the list, then create a "blank" menuTemplate items for the View details, etc. See JBrowse_Configuration_Guide#Customizing_Right-click_Context_Menus for more details.

How do I access data about my features in my callback or plugin

Each feature is based on what is called a feature Model. The JBrowse/Model/SimpleFeature is an example of this, and it allows you to call feature.get('variable_of_interest') on many different variables

Common types of requests

  • feature.get('subfeatures') - to get all subfeatures of a feature.
  • feature.get('parent') - for the parent of a feature
  • feature.get('id') - for the ID
  • feature.get('name') - for the name
  • feature.get('my_gff_field') - to get any given field from your GFF3 column 9
  • feature.get('GT') - to get the genotypes of a VCF feature, it returns a complex object that you can inspect. See "variantIsHeterozygous" in the jbrowse configuration guide for an example of parsing the genotype
  • feature.get('start') - to get start position
  • feature.get('end') - to get end position
  • feature.get('seq_id') - to get the chromosome name
  • feature.get('seq') - to get the sequence, only works on BAM data since it includes sequence data in data file. In general, you must use getReferenceSequence over a region to get a feature's sequence

Note that if you have multiple values for a value in column 9 (specified by comma separated values), then feature.get('your_value') will return an array

For reference JBrowse/Model/SimpleFeature is a widely used feature class. The BAM features for example use a different model because they must be smaller and quicker to operate at speed (they are called Lazy features, so not all their info is evaluated unless it is needed on-demand). BAM features also have things like feature.get('seq'), to get the sequence of the alignments, but normal features like genes do not have feature.get('seq')

How to get default tracks to display every time a user opens the browser?

There are several config variables which you can define in any of your config files (trackList.json for example can have config items like this, just put it outside of the track section of tracklist.json, or under a [general] section of tracks.conf) as a comma separated list of track labels

  • alwaysOnTracks: Track always come up
  • forceTracks: Overridden by URL bar
  • defaultTracks: Overridden by URL bar and cookies

How can I embed JBrowse on a page

The easiest way to "embed jbrowse" on another page would be to use an iframe to link to the jbrowse instance of choice e.g.

Note that it is also possible in theory (and sometimes in practice) to embed JBrowse without an iframe. For example, you can take the index.html of JBrowse and customize it for your purposes. You can for example change the GenomeBrowser div to not have 100% width and height, and instead make it have width 1000px and height 800px for example and put it in a specific part of your webpage.

The problem with embedding without iframe is typically that you can easily run into issues with "CSS collisions" where the CSS from your specific page collides with jbrowse elements, of CSS from jbrowse elements collides with your outside page.

Can I change the color of bases in the Sequence/Alignments2/SNPCoverage tracks?

Yes. It is sort of a "hidden setting", but you can actually change colors on the Sequence/Alignments2/SNPCoverage track using CSS

See css/sequence.css:

/* colors for bases must be specified as hex or rgb/hsl strings, no named colors such as 'red' */
.base_n {
    background-color: #C6C6C6;
.base_a {
    background-color: #00BF00;
.base_c {
    background-color: #4747ff;
.base_t {
    background-color: #f00;
.base_g {
    background-color: #d5bb04;
.base_reference {
    background-color: #a33;
.base_deletion {
    background-color: #999;

If you change those, it will be reflected in your Sequence/Alignments2/SNPCoverage track.

The .base_reference is the background grey of the SNPCoverage plot, and if you actually add to the list and make .base_skip you can make the intron grey change color SNPCoverage.

How can I link BLAST results to JBrowse

If you use sequenceserver, you create a custom JBrowse link by creating a links.rb file and running

sequenceserver -D database_dir -r links.rb

Where links.rb is something like this

require 'json'
module SequenceServer
   module Links
       def jbrowse
           qstart =
           sstart =
           qend =
           send =
           url = ""
           if accession.include? "animal1"
               mid = accession.sub(/^animal1-/, )
               organism = "animal1"
           elsif accession.include? "animal2"
               mid = accession.sub(/^animal2-/, )
               organism = "animal2"
           elsif accession.include? "animal3"
               organism = "animal3"
               mid = accession.sub(/^animal3-/, )
               return nil
           my_hash = [{
               :seq_id => mid,
               :start => sstart,
               :end => send,
               :type => "match",
               :subfeatures => { |hsp| {:start => hsp.send<hsp.sstart ? hsp.send : hsp.sstart, :end => hsp.send<hsp.sstart ? hsp.sstart : hsp.send, :type => "match_part" } }
           my_json = ERB::Util.url_encode(JSON.generate(my_hash))
           my_track = ERB::Util.url_encode(JSON.generate([{"label":"BLAST","key": "BLAST hits","type":"JBrowse/View/Track/CanvasFeatures","store":"url", "glyph": "JBrowse/View/FeatureGlyph/Segments"}]))
           url = "{organism}&loc=#{mid}:#{sstart}..#{send}&addFeatures=#{my_json}&addTracks=#{my_track}&tracks=BLAST"
             :order => 2,
             :title => 'JBrowse',
             :url   => url,
             :icon  => 'fa-external-link'

This code has the the following stipulations

  1. if you have multiple organisms, then the sequence identifiers in your blast database must contain the organism name e.g. every > line in your fasta file should be formatted like "animal1-sequence123" (The reason is that sequenceserver and blast itself doesn't tell you which database the result came from, so encoding the info in the fasta sequence IDs is the only efficient way)
  2. that you are blasting actual genome coordinates, e.g. it won't translate a CDS blast database into genome coordinates for JBrowse (however if individual CDS were loaded as sequences into jbrowse that could work, but that is an abnormal usage of jbrowse)

Note that if you are running sequenceserver through apache, then you instead modify to have a "require './links.rb'" line e.g.

require 'sequenceserver'
require './links.rb'
SequenceServer.init(:config_file => ".sequenceserver.conf")
run SequenceServer


Can I get started with JBrowse without all the fuss of and what-not

Yes! Try the jbrowse desktop versions, built with electron!

The Windows and OSX versions are easy to use, and all you need is to open your fasta file (ideally: indexed fasta).

You can also open BAM tracks, BigWigs, VCF.gz, and soon, Tabix indexed GFF.

Can I install the perl packages using cpanm?

Yes! The packages are not hosted on cpan, but you can install them from github using cpanm

cpanm git://

This will install jbrowse scripts such as and to, commonly, a folder like ~/perl5/bin if you are using local::lib, or simply a system folder like /usr/local/bin if using sudo.

There are a couple scripts that don't work with this such as maker2jbrowse, but it is otherwise fine to install the perl scripts this way.

Note: you might also use --notest option to avoid testing all dependencies

Why does my trackList.json contain "className" (even on CanvasFeatures?)

className refers to a CSS class for your features.

If you are using CanvasFeatures, this is an unused artifact.

If you are using HTMLFeatures, then you can add custom CSS to make your feature have a custom class. Note that the "subfeatureClasses" is a related variable: it is a CSS class for subfeatures.

By default, it would just use the "exon" class for exons or whatnot, but subfeatureClasses allows you to create a map e.g.

"subfeatureClasses": {"exon": "myCustomExonCSSClass"}

How do I create a Tabix indexed GFF

The most reliable way to do this is to use gff3sort from

See for a description of their algorithm

Note that you can try and use GNU sort (sort -k1,1 -k4,4n) or genometools (gt gff3 -sortlines) but these both have problems where it will place child features behind the parent features in the GFF

How do I create a Indexed FASTA?

JBrowse 1.12+ allow opening FASTA files directly in the browser or via JBrowse Desktop. Indexed FASTA is however much more efficient as it does not require being read into memory.

To create an Indexed FASTA, install samtools and run

samtools faidx yourfile.fa

This will create a file called yourfile.fa.fai. When you want to open up your own sequence file in JBrowse, you can then use the "Open sequence file" option, and drag and drop both the .fa and the .fai in the file area. JBrowse will understand that these are to be used together, and will open it.

Note: you can also open unindexed FASTA, but it requires parsing the whole FASTA up front, so this is slow and memory intensive with the current setup. Indexed FASTA is quite efficient though.


Can I speed up JBrowse load time with VCF and BAM files

If the BAM and VCF files you have are large, the BAM index or TABIX index files can become large as well. Since the indexes must be fully downloaded before any of the data can be displayed, you can break your files up by chromosomes, and use {refseq} in a urlTemplate to break it up into manageable chunks.


"urlTemplate": "myfile_{refseq}.bam"

That would search for myfile_chr1.bam and myfile_chr1.bam.bai when you open that track while browsing chr1

Can I add a loading bar while JBrowse is starting up?

Yes, you can configure one. See this section

You could also listen for other milestone events to trigger other loading events (see DebugEvents plugin for details)

Can I speed up

Try using --completionLimit 0 with the command. It will disable autocompletion but still allow you to search exact matches.

Track selector customization

How do I add categories to the Hierarchical data selector?

The hierarchical data selector can support multiple levels of drop down categories. To use this, set the "category" variable on your track, and use a "/" to represent a subcategory. Use multiple / for multiple subcategories.


     "category": "ParentCatgory / DiseaseBAM",
     "label": "myTrack",
     "storeClass": "JBrowse/Store/SeqFeature/BAM",
     "type": "Alignments2";
     "category": "ParentCatgory / NonDiseaseBAM",
     "label": "myTrack2",
     "storeClass": "JBrowse/Store/SeqFeature/BAM",
     "type": "Alignments2";

In tracks.conf form

category=ParentCategory / DiseaseBAM

How do I collapse categories in the Hierarchical data selector by default?

You can set add


etc. to your jbrowse.conf. This is a comma separated list (don't include spaces around the slashes though). Remember, don't quote the values in the jbrowse.conf file :)

Data loading tips

How can I only load a specific type of feature from my GFF file?

You can use the --type argument for

E.g. --type mRNA —gff mygff.gff

This will only load mRNAs from the GFF. Additionally, if you want to filter on the source column of the GFF, you can augment the --type argument with an extra formatted parameter for source --type mRNA:augustus

The --type argument can also be a commas separated list of filters like this.

What if I dont want to load the sequence data for the genome, but I want to display the features? accepts a --sizes parameter, which takes a "chrom.sizes" file which is just a tab separated file with two columns, refseq names and their lengths

This let's you view the genome and the features on the genome without loading the sequence data.


How do I install a plugin

To install a JBrowse plugin, generally the easiest thing to do is to put the code in the plugins directory (e.g. plugins/GCContent and plugins/SashimiPlot), and then just say this in your jbrowse.conf

plugins += GCContent
plugins += SashimiPlot

Equivalently, in jbrowse_conf.json, that would mean just having

"plugins": ["GCContent", "SashimiPlot"]

Essentially, you are just giving the configuration an array of folder names to look for in the plugins directory

Alternatively, you can also add the "name" and "location" of the plugin too.

[ plugins.GCContent ]
location = plugins/gccontent

Here "plugins.GCContent" means that the "name" of your plugin is "GCContent". This is slightly important, because the "name" is is used for the purposes of the "namespace" that the plugin has i.e., when you specify a track with the "type": "GCContent/View/Track/GCContentXY" in trackList.json, then that means the "name" of the plugin should be GCContent, not lowercase gccontent.

Note that this would be equivalent to this in the json format

"plugins": [{
    "name": "GCContent",
    "location": "plugins/gccontent"

The "location" is a relative URL to the jbrowse root directory. Normally when a plugin is successfully installed, you will get a console.log message from the plugin saying that it has started up (that depends on the plugin but most jbrowse plugins just do that by convention)

Note: you can add plugins declarations to trackList.json or tracks.conf. In tracks.conf just put it at the top of the file or underneath a line that says [GENERAL]

Can I create an adaptor for an existing web service?

If your web service doesn't exactly match the requirements for the JBrowse REST API tracks, then you can create your own "store class" as a plugin. This basically just requires one thing:

bin/ MyPlugin 

Then, simply make a dojo class (using "dojo declare") in your plugin that implements a "getFeatures" function. The getFeatures function receives a query object with query.start, query.end, query.ref e.g. chr1 along with 3 callbacks: featureCallback, finishCallback, and errorCallback. If there is an error, than call the error callback obviously. Otherwise, for each feature that you want to display, call featureCallback with that (use JBrowse/Model/SimpleFeature to represent the feature). When you are out of features for the query region, call finishCallback.

Check out the genes store class from the myvariantviewer plugin for an example of a simple custom adaptor

What is a plugin useful for?

A JBrowse plugin can do a wide variety of things. Some common use-cases would be

  • making a custom track type or visualization
  • making an adapter for a new file type or "store class"
  • adding new pieces to the user interface

Other things that are extensible include

One cool thing is that when you create a plugin, you can simply reference it textually in your config file e.g. trackList.json, and then JBrowse will load the "class" from your plugin and initialize it

What background should I have for creating a plugin

Make sure to review this link describing dojo declare, the way dojo declares new object types

Also review

Understanding "*dojo declare*" and *asynchronous module definition (AMD)* will help you understand the “preamble” on the top of every file that jbrowse uses, and which you can use in your plugin

How do I create a plugin?

Let's walk through a simple plugin with the goal of adding something to the track menu (e.g. where the "About this track" and "Save track data" options are)

To do this, we can use object- oriented principles to “inherit” from some existing track type like CanvasFeatures and then extend its functionality by overriding the functions in a new track type

We can inherit a new track type by using the “define” function to include the dependencies needed in a file, and they are listed in an array at the top of your file.

First initialize a new plugin using

bin/ MyPlugin

Then edit a new file, say plugins/MyPlugin/js/MyTrack.js

define( ["dojo/_base/declare", "JBrowse/View/Track/CanvasFeatures"],
   function(declare,CanvasFeatures) {
   return declare(CanvasFeatures, {
       _trackMenuOptions: function() {
           var opts=this.inherited(arguments); //call the parent classes function
           opts.push( // add an extra menu item to the array returned from parent class function
                   label: "Custom item",
                   type: 'dijit/CheckedMenuItem',
                   onClick: function(event) {
                   iconClass: "dijitIconPackage"
           return opts;

Code listing 1. an example custom track type, plugin/MyPlugin/js/MyTrack.js, that adds an extra track menu item

After this, we will have the plugin directory structure like this


The bin/ helps create the skeleton main.js

Then we can use our new plugin to a config file like jbrowse_conf.json as "plugins": ["MyPlugin"]

Then edit the trackList.json for an existing track and change `"type": "CanvasFeatures"` to `"type": "MyPlugin/MyTrack"`.

That will tell jbrowse to load the MyTrack class from your plugin instead of the normal CanvasFeatures class.

Troubleshooting "Installing perl prerequisites" fails for me, why?

Inspect your setup.log

If for example it says

version.c:30:16: fatal error: db.h: No such file or directory

Then run

sudo apt-get install libdb-dev

Then re-run

If you see errors for XML::Parser

sudo apt-get install libexpat1-dev

Then re-run

Also make sure you use "./" or "bash", do not use "sh"

Should I be worried about the error "Building and installing legacy wiggle format (superceded by BigWig tracks)...failed"?

This error is often due to some system issues about compiling libraries like libpng, and for all intents and purposes can be ignored, as it is only used in and this is superceded by directly reading BigWig files (no conversion step needed)

You can follow these instructions for how to setup a BigWig file if needed

I see a message that says "Congratulations, JBrowse is on the web" but I don't see my genome

This message normally means that jbrowse is setup but a genome hasn't been loaded or located correctly

You can continue by running

 bin/ --fasta yourfile.fa

Then reload the page and your genome should be available.

Note: If the red box on the "Congratulations page" shows a different message than just 404 on seq/refSeqs.json, then report the error to github or the mailing list with as much detail about your setup as possible.

What is this error during "No such file or directory at /loader/0x13517b30/App/cpanminus/ line 224."

This can normally be fixed by deleting ~/.cpanm

It may be due to conflict between jbrowse's own cpanm and your system cpanm, but it should not be too problematic.

Generally deleting ~/.cpanm is harmless, it is a "build" directory (generally ~/perl5 is the local::lib directory, and in jbrowse's case, it actually uses an alternate local::lib directory named extlib inside the jbrowse directory to ensure ease-of-install)

What is "Integer overflow error"?

From what we have seen, the "Integer overflow error" sometimes appears on BigWig tracks when your webserver is not configured correctly. It seems to be due to errors with a "reverse proxy" or something not forwarding the data properly.

Therefore, it is most likely not due to corrupted bigwig files or jbrowse bugs, but more probably, due to your server's configuration.

Why do I get a popup saying "Error reading from name store"?

This error basically says the "search function" from isn't working. You can try a couple things to fix the error

  1. Refresh your browser (especially in Apollo, where session can expire)
  2. Re-run
  3. Re-run --hashBits 16 (manually specifying the hashBits can fix error sometimes)
  4. Re-run with --completionLimit 0 which disables autocomplete and makes index smaller
  5. Make sure that the fields you are indexing (e.g. Name or ID) don't contain full text descriptions (they should be symbols or identifiers, the default hash search won't index keywords but rather match prefixes)

Note if there are continued troubles, you can try an alternative search engine, such as jbrowse_elasticsearch (an experimental plugin)

What is this error message "Argument isn't numeric in addition (+)" loading GFF3?

If you get an error similar to this:

_Argument "-" isn't numeric in addition (+) at /Library/WebServer/Documents/scbrowse/JBrowse-1.12.0/bin/../src/perl5/Bio/JBrowse/FeatureStream/ line 32, <$f> line 44611._

Make sure your GFF3 is tab delimited

It keeps showing "too much data" on my track. How do I fix it and make my track display?

Increase maxFeatureScreenDensity to a higher value. This value is by default 0.5 but if you allow a higher "density" of features, set it to 6 for example and the message should disappear.

I get the error "Too much data...chunk size xxxxx exceeds chunkSizeLimit"

Several things can happen to cause this (generally on VCF of BAM tracks)

  1. You actually have exceeded the chunkSize during regular loading of data. You might see one specific block/region out of your whole track is giving this error. In this case, simply increase it.
  2. Your data is actually fairly sparse so when it first starts up, the "stats estimation routine", which "doubles" the region it searches in until it gets enough data, is failing. If it doubles too many times, then the chunk will become large and then hit the limit. In JBrowse 1.12.3 a "statsTimeout" configuration was introduced to avoid these doublings from consuming too much area.

I set a value in my config file but it isn't working. Why not?

Some things to check:

  • Don't add quotes around numerical values in your JSON config files e.g. trackList.json. Numbers can remain unquoted. Booleans can too. Functions are included in quotes though, because those are evaluated at runtime.
  • Also don't add quotes around even the strings in the .conf config files e.g. jbrowse.conf or tracks.conf files. So use defaultTracks=mytrack1,mytrack2 not defaultTracks="mytrack1,mytrack2"
  • Clear your cache. JSON is often cached pretty strongly. The .conf are cached even more. And, additionally, if there is a syntax issue with your JSON, it will try and use an older version oftentimes until you clear cache.

Also note: specifically with regards to the "defaultTracks" parameter, defaultTracks is overridden by the users cookies and the &tracks= parameter in the URL, so to test whether defaultTracks works, clear you cookies and visit without &tracks in the url. Use alwaysOnTracks or forceTracks if you want to have it turn on despite cookies/URL.

I get the error "Too many open files opening bucket log" with

If you get the error such as this

Too many open files opening bucket log /path/to/your/data/names/00f/6.json.log at perl5/lib/perl5/Bio/JBrowse/ line 197, <$fh> line 85.

Then try increasing number of files available

ulimit -n 1000

The default can sometimes be as low as 256 (view with ulimit -a)

How do I fix the "Not a BAM file" issue?

This is normally due to a module called mime_magic being enabled on your Apache server. Two options for fixing this are 1. disable mime_magic or 2. configuring custom file types with AddType in your apache configuration. See JBrowse_Configuration_Guide#Apache_Configuration_Note for recommended fixes.

What is the error "invalid BGZF header" on my VCF files?

Your server is misconfigured for VCF.GZ files, and this can be due to it thinking that it should set "Content-Encoding: gzip" on the your .vcf.gz files. Your webserver should actually NOT put "Content-Encoding: gzip" on your VCF.GZ files. If you think you have this problem, can try using "curl -I" to view the headers that your server is putting on your VCF.GZ file.

Note: this issue can be confusing to research about, especially the "Content-Encoding: gzip" issue, because most information on the web typically says that it should put "Content-Encoding: gzip" on gzip data, and this header implies that the client should decompress the content itself, however JBrowse does not want this to happen because VCF.gz files are a special type of gzip, specifically, bgzip, so it is manually decompressed by JBrowse javascript code.

My track doesn't display the gene names, but I expected it to. Why not?

If you have a very dense track with many features, JBrowse might decide to hide the labels to save space, but you can force them to display again by adding this to your trackList.json

"style":{"labelScale": 0.01}

This says that the label will be displayed when the zoom level is greater than 0.01 regardless of how many features are there. The value 0.01 is measured in pixels per base pair, at max zoom level, there are 25 pixels per base pair for example, and when zoomed out farther, each base takes up less space, hence 0.01 will display the feature names always if you are reasonably zoomed in.

You can also change maxHeight to a larger value to make the track taller and see more features.

Why does my track keep saying "Loading"?

This normally means some javascript code for handling the track has crashed. Check your javascript console for clues on how to fix it. Add a github issue if it represents a real bug!

Note: you should use the "-dev" packages for debugging, i.e. as opposed to for example, because the -dev package contains "un-minified" source code and more readable javascript console messages

My CanvasFeatures don't show up with subfeatures, why not?

If your GFF does not follow this structure


Then you need to add extra configuration

Specifically, if it is "transcript" instead of "mRNA" (which is common for Ensembl GFF for example), then you must set

"transcriptType": "transcript"

Also, if you only have "exon" and no "CDS", then you need to set the subParts config (the default settings assumes that both exons and CDS exist, so if there are only exons, like in a cufflinks output file, then you need this)

"subParts": "exon"

If your GFF does not include UTR, but the UTR can be "implied" from the difference between the exon and CDS boundaries, then you can use this on your track type to enable them

"impliedUTRs": true

If your GFF file has features with this structure

match -> match_part

This only has two levels, you might consider just setting the "Segments" glyph

"glyph": "JBrowse/View/FeatureGlyph/Segments"

The segments glyph accepts all subfeatures, so match and match_part structure is fine.

Note: the tips above only apply for CanvasFeatures tracks

My HTMLFeatures don't show up with subfeatures, why not?

HTMLFeatures generally load data at the "transcript" level. This means that they should be loaded with something similar to --type mRNA when using in order to see the transcript subfeatures --type mRNA --gff your_genes.gff --trackLabel MyTrack

This means that it loads the features where mRNA would be in column 3 of your GFF. If it was an Ensembl GFF, you might use instead --type transcript

Note that this also loses the information about the "parent" gene feature however, so it might be worth loading an additional track at the gene level like --type gene --gff your_genes.gff

This track will not display the transcript and exon subfeatures, but instead just show a box where the gene is, so this is commonly called a "gene spans" track

Note: If you would like a track that displays with the transcript subfeatures, you can use the CanvasFeatures type track (i.e. load with --type gene --trackType CanvasFeatures ...)

Why are my subfeatures being displayed as separate features?

Your GFF should use proper ID and Parent relations. Your subfeatures do not need to themselves have IDs if they have no further subfeatures, but they must have a Parent pointing to the Parent's ID

Note that it should be spelled Parent, not PARENT

I get the error "Building and installing legacy support (superseded by direct BAM tracks) ... failed"

If you get the error "Building and installing legacy support (superseded by direct BAM tracks) ... failed. See setup.log file for error messages. If you really need (most users don't), try reading the Bio-SamTools troubleshooting guide at for help getting Bio::DB::Sam installed."

Then note:

  • This error message can be ignored. It refers only to not being able to run a small outdated feature of jbrowse.
  • If you want to fix it, the issue might refer to a conflict with the system version of samtools. Uninstall your system samtools and then re-run (notably homebrew samtools causes this step to fail)
  • Again, this only refers to, which converts entire BAM files to json. It is better to use the which simply can read BAM files directly from the server with no conversion.

After I load my track it appears in the tracklist, but the track appears empty

This can happen if the chromosome names from your track don't match the names from your reference genome.

Try and make sure the chromosome names from your evidence tracks match the chromosome names from the reference genome fasta.

My BigWig file is producing an error related to DataView or jDataView

Examples of error messages

  • RangeError: Offset is outside the bounds of the DataView (Chrome)
  • Error: jDataView length or (byteOffset+length) value is out of bounds (Firefox)
  • RangeError: Out of bounds access (Safari)
  • RangeError: Argument 1 accesses an index that is out of range (Firefox)

Check that

  • The file that you are using is actually the right filetype (i.e. maybe it is a textfile, but you are giving it a bigwig file extension)
  • The webserver you are using allows Range HTTP headers (apache, nginx, etc should allow this by default)
  • That you aren't simply opening up your index.html without a webserver i.e. using file:/// protocol (which will not allow accessing byte-range Range HTTP requests and cause this error)

Tips and tricks

How can I get jbrowse to update the URL of a parent page when jbrowse is inside of an iframe

You can use code such as this

<iframe id="jbrowse_iframe" src="/jbrowse/" scrolling="no" style="width:100%;height:800px;"></iframe>
function getQueryVariable(variable) {
    var query =;
    var vars = query.split('&');
    for (var i = 0; i < vars.length; i++) {
        var pair = vars[i].split('=');
        if (decodeURIComponent(pair[0]) == variable) {
            return decodeURIComponent(pair[1]);
// subscribe to jbrowse movements inside of the iframe and update parent page url
var datadir = getQueryVariable('data');
var iframe = document.getElementById('jbrowse_iframe');
iframe.addEventListener('load', function() {
    var JBrowse = iframe.contentWindow.JBrowse;
    JBrowse.subscribe( '/jbrowse/v1/n/navigate',  function(obj) {
        var shareURL = JBrowse.makeCurrentViewURL();
        var parser = new URL(shareURL);
        window.history.replaceState( {}, "", );
// pass the parameters from the parent page into the iframe
iframe.src = iframe.src +;

With this setup, you can pass URL parameters from the URL of the parent page e.g. http://localhost/parent_page/?data=mydata&loc=chr1:1..10000 and it will forward those URL params to the jbrowse instance (located at http://localhost/jbrowse) and the URL will be autoupdated when you change locations

Can I use JBrowse with phantomJS?

Yes! See for an example

How do I convert GTF to GFF

Since does not accept GTF, you can convert your GTF to GFF3. Tools like gffread or are available

The gffread tool is packaged with cufflinks so simply install cufflinks, then you can run

gffread -E merged.gtf -o- > merged.gff3

Can I run JBrowse on GitHub pages?

Yes! Upload jbrowse to a gh-pages branch on a github repo, and also put a .nojekyll file in the root directory.

This bypasses the normal jekyll parser of github and allows jbrowse to load

What is the benefit of using

  • You can store more advanced creation in the conf file, allowing for more advanced and reproducible builds of your data directory
  • You can load data from different sources like Chado, GFF, etc.

In general, using normal commands like flatfile-to-json, prepare-refseqs, etc work fine though. See for how the volvox sample data combines using biodb-to-json and other techniques.

Visualization tips

Can I make an ultra-compact setting on my features?

Yes you can!

The styles on "CanvasFeatures" include normal, compact, and collapse

By default, compact divides the height of glyphs by 4, so if you make the height of your features smaller with style->height then when you set compact it will be ultra compact.

Can I disable the histograms on a track?

Yes! Try setting style.featureScale to a very small number like 0.0000000001 (but greater than 0)

Can I visualize junctions from RNA-seq data

Yes, try out the SashimiPlot plugin!

It dynamically calculates the splicing coverage of a track or uses junctions.bed files for junctions

Can I view GCContent on my sequence data?

Yes, the GCContent plugin will calculate the GCContent from your sequence data automatically. See

It works fairly well on mid-size genomes. If you have very large megabase scale assemblies, then you might consider pre-calculating the GCContent.

Can I view GWAS results in JBrowse?

Yes, the GWASViewer plugin does this.

What do the colors mean on the BAM files for JBrowse

  • Light red is a forward read that is paired
  • Super light red is a forward read that is badly paired
  • Dark red is a forward read that is missing a pair
  • Light blue is a reverse read that is paired
  • Super light blue is a reverse read that is badly paired
  • Dark blue is a reverse read that is missing a pair
  • Grey/black is a read whose pair is on another chromosome

Can I use RNA-seq with JBrowse

Yep! The regular alignments track types (e.g. JBrowse/View/Track/Alignments2) supports RNA-seq and will show spliced alignments.

Also, there are two special options for RNA-seq that can help decipher the reads.

  • The "Use XS" option is a RNA-seq specific flag that aligners output which detects the strand that a read came from according to canonical splice site. Enable in config using useXS: true
  • The "Use reversed template" option is flag normally used for "stranded paired-end RNA-seq" data  and it will make both reads in a pair look like they are in the same direction, so for example, reads from a plus-strand gene will all appear red, even when one of the reads in the pair would normally be blue. Enable in config with useReverseTemplate: true

Can I use long reads with JBrowse?

Long reads from platforms like nanopore and pacbio pose some challenges but will work if it is in BAM format. The JBrowse 1.12.3 release also includes an optimization, cacheMismatches, to enhance speed on long read tracks. This must be enabled manually in the config at the moment.

Can I have subtracks in JBrowse?

You can make a custom plugin to do this. The "multibigwig" plugin is an example of this

How do I get coverage for a BAM file?

  1. Use the SNPCoverage track
  2. Use the FeatureCoverage track type
  3. Make a bigwig for your BAM file (recommend: use "bedtools genomecov" to convert the BAM to bedgraph, and the convert bedgraph to bigwig with UCSC bedGraphToBigWig)

Also note: with the third option, you can make it so that your BAM track has a bigwig when zoomed out, but then shows the reads when zoomed in. Any CanvasFeatures track can use a bigwig for summary histograms. The Alignments2 volvox-sorted.bam track is an example of this. See

Can I zoom even closer to the base level?

Yes. You can set the config variable view.maxPxPerBp to a higher value. To increase, try setting this in jbrowse.conf


Note sometimes the "translations" will appear wrong at high zoom levels, so don't depend on this for the protein translations

By default, the max zoom level is 25, so setting it to 50 makes you able to zoom in twice as much.

How do I change the color of bigwig dynamically

The pos_color and neg_color config variables for BigWig tracks accept callback functions. The phytozome browser has good examples of this with the VISTA plot tool