Note: If you do not plan to make any code changes yourself, and only wish to run the latest prerelease versions of Zotero, you can just install a development build.

Zotero code is available under the AGPLv3 license, except where the source code specifies otherwise.

Zotero source code is hosted on GitHub.

Zotero's Git repositories often have multiple branches for different lines of development. The default branch, master, is the main development branch where development is most active and where most new features are first introduced. Because of this, master code may be less stable and may be riskier for production use. Once a major version has been out for a while, a branch is created, and that branch then receives mostly bug fixes and small changes. When a release is made (e.g., Zotero 5.0.30), a snapshot of the relevant code is tagged with its version number. See Git documentation for more information on working with branches and tags.

Zotero does not use GitHub Issues for bug reports or feature requests. Please post all such requests to the Zotero Forums, where Zotero developers and many others can help. Keeping product discussions in the Zotero Forums allows the entire Zotero community to participate, including domain experts that can address many questions better than Zotero developers.

For confirmed bugs or agreed-upon changes, Zotero developers will create new issues in the relevant repositories.

Zotero developers previously used Trac as a source code browser and internal issue tracker, and very old tickets are still archived there.

See Building the Zotero Client.

To run a Git build of the Google Chrome Connector, you need to:

• git clone --recursive https://github.com/zotero/zotero-connectors/
• cd zotero-connectors
• npm i
• ./build -d && gulp
• Run Zotero and Chrome
• Load the Connector extension in Chrome
  1. Browse to chrome://extensions/
  2. Expand the “Developer mode” bar
  3. Click the button “Load unpacked extension…”, and give the path to the build/browserExt directory within the local repository

You should now see a Zotero icon in the address bar when visiting translatable webpages (e.g., this article or this book), and clicking the icon should add the item to your Zotero library.

After making changes, click Reload for the Connector entry in the Chrome Extensions pane and reload any open pages where you want to use the Connector. (If gulp isn't running, you'll need to run ./build -d after each change.)

The preferred way to contribute code is to fork the relevant Git repository, commit your changes, and send a pull request.

See Client Coding for more information on coding for Zotero.