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API Documentation Browser

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Statistics on devdocs

Number of watchers on Github 17193
Number of open issues 59
Average time to close an issue 7 days
Main language Ruby
Average time to merge a PR 6 days
Open pull requests 37+
Closed pull requests 106+
Last commit about 1 year ago
Repo Created over 5 years ago
Repo Last Updated about 1 year ago
Size 13.4 MB
Organization / Authorthibaut
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DevDocs Build Status

DevDocs combines multiple API documentations in a fast, organized, and searchable interface.

Keep track of development news:

Table of Contents: Quick Start Vision App Scraper Commands Contributing License Questions?

Quick Start

Unless you wish to contribute to the project, I recommend using the hosted version at It's up-to-date and works offline out-of-the-box.

DevDocs is made of two pieces: a Ruby scraper that generates the documentation and metadata, and a JavaScript app powered by a small Sinatra app.

DevDocs requires Ruby 2.5.0, libcurl, and a JavaScript runtime supported by ExecJS (included in OS X and Windows; Node.js on Linux). Once you have these installed, run the following commands:

git clone && cd devdocs
gem install bundler
bundle install
bundle exec thor docs:download --default
bundle exec rackup

Finally, point your browser at localhost:9292 (the first request will take a few seconds to compile the assets). You're all set.

The thor docs:download command is used to download pre-generated documentations from DevDocs's servers (e.g. thor docs:download html css). You can see the list of available documentations and versions by running thor docs:list. To update all downloaded documentations, run thor docs:download --installed.

Note: there is currently no update mechanism other than git pull origin master to update the code and thor docs:download --installed to download the latest version of the docs. To stay informed about new releases, be sure to watch this repository.

Alternatively, DevDocs may be started as a Docker container:

# First, build the image
git clone && cd devdocs
docker build -t thibaut/devdocs .

# Finally, start a DevDocs container (access http://localhost:9292)
docker run --name devdocs -d -p 9292:9292 thibaut/devdocs


DevDocs aims to make reading and searching reference documentation fast, easy and enjoyable.

The app's main goals are to: keep load times as short as possible; improve the quality, speed, and order of search results; maximize the use of caching and other performance optimizations; maintain a clean and readable user interface; be fully functional offline; support full keyboard navigation; reduce context switch by using a consistent typography and design across all documentations; reduce clutter by focusing on a specific category of content (API/reference) and indexing only the minimum useful to most developers.

Note: DevDocs is neither a programming guide nor a search engine. All our content is pulled from third-party sources and the project doesn't intend to compete with full-text search engines. Its backbone is metadata; each piece of content is identified by a unique, obvious and short string. Tutorials, guides and other content that don't meet this requirement are outside the scope of the project.


The web app is all client-side JavaScript, written in CoffeeScript, and powered by a small Sinatra/Sprockets application. It relies on files generated by the scraper.

Many of the code's design decisions were driven by the fact that the app uses XHR to load content directly into the main frame. This includes stripping the original documents of most of their HTML markup (e.g. scripts and stylesheets) to avoid polluting the main frame, and prefixing all CSS class names with an underscore to prevent conflicts.

Another driving factor is performance and the fact that everything happens in the browser. applicationCache (which comes with its own set of constraints) and localStorage are used to speed up the boot time, while memory consumption is kept in check by allowing the user to pick his/her own set of documentations. The search algorithm is kept simple because it needs to be fast even searching through 100,000 strings.

DevDocs being a developer tool, the browser requirements are high:

  1. On the desktop:
    • Recent version of Chrome, Firefox, or Opera
    • Safari 8+
    • IE / Edge 10+
  2. On mobile:
    • iOS 8+
    • Android 4.1+
    • Windows Phone 8+

This allows the code to take advantage of the latest DOM and HTML5 APIs and make developing DevDocs a lot more fun!


The scraper is responsible for generating the documentation and index files (metadata) used by the app. It's written in Ruby under the Docs module.

There are currently two kinds of scrapers: UrlScraper which downloads files via HTTP and FileScraper which reads them from the local filesystem. They both make copies of HTML documents, recursively following links that match a set of rules and applying all sorts of modifications along the way, in addition to building an index of the files and their metadata. Documents are parsed using Nokogiri.

Modifications made to each document include:

  • removing content such as the document structure (<html>, <head>, etc.), comments, empty nodes, etc.
  • fixing links (e.g. to remove duplicates)
  • replacing all external (not scraped) URLs with their fully qualified counterpart
  • replacing all internal (scraped) URLs with their unqualified and relative counterpart
  • adding content, such as a title and link to the original document

These modifications are applied via a set of filters using the HTML::Pipeline library. Each scraper includes filters specific to itself, one of which is tasked with figuring out the pages' metadata.

The end result is a set of normalized HTML partials and two JSON files (index + offline data). Because the index files are loaded separately by the app following the user's preferences, the scraper also creates a JSON manifest file containing information about the documentations currently available on the system (such as their name, version, update date, etc.).

More information about scrapers and filters is available on the wiki.

Available Commands

The command-line interface uses Thor. To see all commands and options, run thor list from the project's root.

# Server
rackup              # Start the server (ctrl+c to stop)
rackup --help       # List server options

# Docs
thor docs:list      # List available documentations
thor docs:download  # Download one or more documentations
thor docs:manifest  # Create the manifest file used by the app
thor docs:generate  # Generate/scrape a documentation
thor docs:page      # Generate/scrape a documentation page
thor docs:package   # Package a documentation for use with docs:download
thor docs:clean     # Delete documentation packages

# Console
thor console        # Start a REPL
thor console:docs   # Start a REPL in the "Docs" module
Note: tests can be run quickly from within the console using the "test" command. Run "help test"
for usage instructions.

# Tests
thor test:all       # Run all tests
thor test:docs      # Run "Docs" tests
thor test:app       # Run "App" tests

# Assets
thor assets:compile # Compile assets (not required in development mode)
thor assets:clean   # Clean old assets

If multiple versions of Ruby are installed on your system, commands must be run through bundle exec.


Contributions are welcome. Please read the contributing guidelines.

DevDocs's own documentation is available on the wiki.

Copyright / License

Copyright 2013-2018 Thibaut Courouble and other contributors

This software is licensed under the terms of the Mozilla Public License v2.0. See the COPYRIGHT and LICENSE files.

Please do not use the name DevDocs to endorse or promote products derived from this software without my permission, except as may be necessary to comply with the notice/attribution requirements.

I also wish that any documentation file generated using this software be attributed to DevDocs. Let's be fair to all contributors by giving credit where credit's due. Thanks!


If you have any questions, please feel free to ask them on the mailing list.

devdocs open issues Ask a question     (View All Issues)
  • over 2 years Shortcuts for back/forward clash with text navigation shortcuts in search field
  • over 2 years URL color template dark mode
  • over 2 years Consider using LZ compression for localStorage
  • over 2 years Sepia theme
  • over 2 years Disable keyboard shortcuts
  • over 2 years link to page doesn't exist
  • over 2 years Rails ActiveSupport::TimeZone MAPPING constant value is missing
  • over 2 years Electron like runner
  • about 3 years Custom doc abbreviations
  • about 3 years Please: is there a way to automatically redirect me to my last reading section?
  • over 3 years feature request - collapse left-hand bar and add shortcut for popup search box
  • over 3 years Add a feature to export/import offline data
  • over 3 years Suggestion: Add a way to swap Up/Down arrow keys with ALT+Up/Down
  • over 3 years Feature to add own set of docs
  • over 3 years JQuery, JQuery ui examples doesn't work while offline
  • almost 4 years Intercept links to known documentation
  • over 4 years DevDocs format for integration into IDE (API)
  • over 5 years Github Readmes From Repos
  • over 5 years Rearranging documentations in the sidebar / results
  • over 5 years Categorize documentations
devdocs open pull requests (View All Pulls)
  • Add Ansible documentation
  • Add Haxe documentation
  • Add documentation for TensorFlow's python API
  • Adding influxdb documentation
  • Version Lua documentation (5.1, 5.2, 5.3)
  • Added Lua Nginx Module documentation
  • Add CodeIgniter Documentation
  • Add Bluebird docs
  • Add double click event to toggle the sidebar
  • Hide/Show sidebar when dragging it or typing into the serarch input
  • Fix URL#relative_path_to
  • Add Kotlin documentation
  • add support for CMake
  • Add LÖVE Documentation
  • Add matplotlib documentation
  • Add Crystal documentation
  • Add Docker documentation
  • Add Bottle Documentation
  • Add usage examples to Go docs
  • Immutablejs
  • Codeception documentation
  • Added Sepia Theme
  • Update React Native documentation (0.40)
  • Fix homepage url for Bottle
  • Update OpenSearch instructions for Firefox
  • Add leaflet doc
  • Replace event.which with event.key in shortcut handlers
  • Refactor clean_html filters
  • Convert external links to other enabled docs to internal links
  • Update Prism
  • Add Jekyll documentation
  • Add JSDoc documentation
  • Adds Scala documentation
  • Add a pull request template
  • README: mention Prism for syntax highlighting
  • Update to security patch nokogiri 1.8.2 for CVE-2017-15412
  • Bump to Ruby patch 2.4.3
devdocs questions on Stackoverflow (View All Questions)
  • Can't installl devdocs for offline browsing
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