Skip to content
Switch branches/tags
Go to file
Cannot retrieve contributors at this time

Contributor Guidelines

Advice for new contributors

Start small. The PRs most likely to be merged are the ones that make small, easily reviewed changes with clear and specific intentions. See below for more guidelines on pull requests.

It's a good idea to gauge interest in your intended work by finding the current issue for it or creating a new one yourself. You can use also that issue as a place to signal your intentions and get feedback from the users most likely to appreciate your changes.

Once you've spent a little bit of time planning your solution, it's a good idea to go back to the issue and talk about your approach. We'd be happy to provide feedback. An ounce of prevention, as they say!

Developer Setup

First, you'll need Node.js which matches our current version. You can check .nvmrc in the development branch to see what the current version is. If you have nvm you can just run nvm use in the project directory and it will switch to the project's desired Node.js version. nvm for windows is still useful, but it doesn't support .nvmrc files.

Then you need git and git-lfs, if you don't have those yet.


Install the Xcode Command-Line Tools.


  1. Windows 7 only:
  2. Install Windows Build Tools: Open the Command Prompt (cmd.exe) as Administrator and run: npm install --vs2015 --global --production --add-python-to-path windows-build-tools


  1. Pick your favorite package manager.
  2. Install python (Python 2.7+)
  3. Install gcc
  4. Install g++
  5. Install make
  6. Install git-lfs

All platforms

Now, run these commands in your preferred terminal in a good directory for development:

git clone
cd Signal-Desktop
git-lfs install                # Setup Git LFS.
npm install --global yarn      # (only if you don’t already have `yarn`)
yarn install --frozen-lockfile # Install and build dependencies (this will take a while)
yarn grunt                     # Generate final JS and CSS assets
yarn build:webpack             # Build parts of the app that use webpack (Sticker Creator)
yarn test                      # A good idea to make sure tests run first
yarn start                     # Start Signal!

You'll need to restart the application regularly to see your changes, as there is no automatic restart mechanism. Alternatively, keep the developer tools open (View > Toggle Developer Tools), hover over them, and press Cmd + R (macOS) or Ctrl + R (Windows & Linux).

Also, note that the assets loaded by the application are not necessarily the same files you’re touching. You may not see your changes until you run yarn grunt on the command-line like you did during setup. You can make it easier on yourself by generating the latest built assets when you change a file. Run this in its own terminal instance while you make changes:

yarn grunt dev # runs until you stop it, re-generating built assets on file changes

If you miss the git-lfs step, run yarn cache clean and remove node_modules before trying again.


Some parts of the app (such as the Sticker Creator) have moved to webpack. You can run a development server for these parts of the app with the following command:

yarn dev

In order for the app to make requests to the development server you must set the SIGNAL_ENABLE_HTTP environment variable to a truthy value. On Linux and macOS, that simply looks like this:


Setting up standalone

By default the application will connect to the staging servers, which means that you will not be able to link it with your primary mobile device.

Fear not! You don't have to link the app with your phone. On the QR code screen, you can select 'Set Up as Standalone Device' from the File menu, which goes through the registration process like you would on a phone.

Note: you won't be linked to a primary phone, which will make testing certain things very difficult (contacts, profiles, and groups are all solely managed on your phone).

The staging environment

Sadly, this default setup results in no contacts and no message history, an entirely empty application. But you can use the information from your production install of Signal Desktop to populate your testing application!

First, exit both production and development apps (In macOS - literally quit the apps). Second, find your application data:

  • macOS: ~/Library/Application Support/Signal
  • Linux: ~/.config/Signal
  • Windows 10: C:\Users\<YourName>\AppData\Roaming\Signal

Now make a copy of this production data directory in the same directory (a sibling of the Signal directory), and call it Signal-development. Now start up the development version of the app as normal, and you'll see all of your contacts and messages!

You'll notice a prompt to re-link, because your production credentials won't work on staging. Click 'Relink', then 'Standalone', then verify the phone number and click 'Send SMS.'

Once you've entered the confirmation code sent to your phone, you are registered as a standalone staging device with your normal phone number, and a copy of your production message history and contact list.

Here's the catch: you can't message any of these contacts, since they haven't done the same thing. Who can you message for testing?

Additional storage profiles

What you need for proper testing is additional phone numbers, to register additional standalone devices. You can get them via Twilio ($1/mo. per number + $0.0075 per SMS), or via Google Voice (one number per Google Account, free SMS).

Once you have the additional numbers, you can setup additional storage profiles and switch between them using the NODE_APP_INSTANCE environment variable.

For example, to create an 'alice' profile, put a file called local-alice.json in the config directory:

  "storageProfile": "aliceProfile"

Then you can start up the application a little differently to load the profile:

NODE_APP_INSTANCE=alice yarn run start

This changes the userData directory from %appData%/Signal to %appData%/Signal-aliceProfile.

Making changes

So you're in the process of preparing that pull request. Here's how to make that go smoothly.


Please write tests! Our testing framework is mocha and our assertion library is chai.

The easiest way to run all tests at once is yarn test.

You can browse tests from the command line with grunt unit-tests or in an interactive session with NODE_ENV=test yarn run start.

If you want to run the libtextsecure tests, you can run yarn run test-electron, which also runs the unit tests.

To run Node.js tests, you can run yarn test-server from the command line. You can get code coverage numbers for this kind of run via yarn test-server-coverage, then display the report with yarn open-coverage.

Pull requests

So you wanna make a pull request? Please observe the following guidelines.

  • First, make sure that your yarn ready run passes - it's very similar to what our Continuous Integration servers do to test the app.
  • Please do not submit pull requests for translation fixes. Anyone can update the translations in Transifex.
  • Never use plain strings right in the source code - pull them from messages.json! You only need to modify the default locale _locales/en/messages.json. Other locales are generated automatically based on that file and then periodically uploaded to Transifex for translation.
  • Rebase your changes on the latest development branch, resolving any conflicts. This ensures that your changes will merge cleanly when you open your PR.
  • Be sure to add and run tests!
  • Make sure the diff between our master and your branch contains only the minimal set of changes needed to implement your feature or bugfix. This will make it easier for the person reviewing your code to approve the changes. Please do not submit a PR with commented out code or unfinished features.
  • Avoid meaningless or too-granular commits. If your branch contains commits like the lines of "Oops, reverted this change" or "Just experimenting, will delete this later", please squash or rebase those changes away.
  • Don't have too few commits. If you have a complicated or long lived feature branch, it may make sense to break the changes up into logical atomic chunks to aid in the review process.
  • Provide a well written and nicely formatted commit message. See this link for some tips on formatting. As far as content, try to include in your summary
    1. What you changed
    2. Why this change was made (including git issue # if appropriate)
    3. Any relevant technical details or motivations for your implementation choices that may be helpful to someone reviewing or auditing the commit history in the future. When in doubt, err on the side of a longer commit message.

Above all, spend some time with the repository. Follow the pull request template added to your pull request description automatically. Take a look at recent approved pull requests, see how they did things.

Linking to a staging mobile device

Multiple standalone desktop devices are great for testing of a lot of scenarios. But a lot of the Signal experience requires a primary mobile device: contact management, synchronizing read and verification states among all linked devices, etc.

This presents a problem - even if you had another phone, the production versions of the iOS and Android apps are locked to the production servers. To test all scenarios in staging, your best bet is to pull down the development version of the iOS or Android app, and register it with one of your extra phone numbers:

First, build Signal for Android or iOS from source, and point its service URL to

on Android: Replace the SIGNAL_URL value in build.gradle

on iOS: Replace the textSecureServerURL value in TSConstants.h(located in the SignalServiceKit pod)

This task is 1% search and replace, 99% setting up your build environment. Instructions are available for both the Android and iOS projects.

Then you can set up your development build of Signal Desktop as normal. If you've already set up as a standalone install, you can switch by opening the DevTools (View -> Toggle Developer Tools) and entering this into the Console and pressing enter: window.owsDesktopApp.appView.openInstaller();

Changing to production

If you're completely sure that your changes will have no impact to the production servers, you can connect your development build to the production server by putting a file called local-development.json in the config directory. It should be a copy of production.json, but you should set updatesEnabled to false so that the auto-update infrastructure doesn't kick in while you're developing.

Beware: Setting up standalone with your primary phone number when connected to the production servers will unregister your mobile device! All messages from your contacts will go to your new development desktop app instead of your phone.

Testing Production Builds

To test changes to the build system, build a release using

yarn generate
yarn build

Then, run the tests using grunt test-release:osx --dir=release, replacing osx with linux or win depending on your platform.


To pull the latest translations, follow these steps:

  1. Download Transifex client:
  2. Create Transifex account:
  3. Generate API token:
  4. Create ~/.transifexrc configuration:
  5. Run yarn grunt tx.