Code of Conduct

Contributors to Tree-sitter should abide by the Contributor Covenant.

Developing Tree-sitter


To make changes to Tree-sitter, you should have:

  1. A C compiler, for compiling the core library and the generated parsers.
  2. A Rust toolchain, for compiling the Rust bindings, the highlighting library, and the CLI.
  3. Node.js and NPM, for generating parsers from grammar.js files.
  4. Either Emscripten or Docker, for compiling the library to WASM.


Clone the repository:

git clone
cd tree-sitter

Optionally, build the WASM library. If you skip this step, then the tree-sitter web-ui command will require an internet connection. If you have emscripten installed, this will use your emcc compiler. Otherwise, it will use Docker:


Build the Rust libraries and the CLI:

cargo build --release

This will create the tree-sitter CLI executable in the target/release folder.


Before you can run the tests, you need to clone some grammars that are used for testing:


To test any changes you’ve made to the CLI, you can regenerate these parsers using your current CLI code:


Then you can run the tests:


Similarly, to test the WASM binding, you need to compile these parsers to WASM:



The test script has a number of useful flags. You can list them all by running script/test -h. Here are some of the main flags:

If you want to run a specific unit test, pass its name (or part of its name) as an argument:

script/test test_does_something

You can run the tests under the debugger (either lldb or gdb) using the -g flag:

script/test test_does_something -g

Part of the Tree-sitter test suite involves parsing the corpus tests for several different languages and performing randomized edits to each example in the corpus. If you just want to run the tests for a particular language, you can pass the -l flag. And if you want to run a particular example from the corpus, you can pass the -e flag:

script/test -l javascript -e Arrays

Published Packages

The main tree-sitter/tree-sitter repository contains the source code for several packages that are published to package registries for different languages:

There are also several other dependent repositories that contain other published packages:

Publishing New Releases

Publishing a new release of the CLI requires these steps:

  1. Commit and push all outstanding changes and verify that CI passes:

    git commit -m "Fix things"
    git push
  2. Create a new tag:

    script/version patch

    This will determine the current version, increment the patch version number, and update the Cargo.toml and package.json files for the Rust and Node CLI packages. It will then create a commit and a tag for the new version. For more information about the arguments that are allowed, see the documentation for the npm version command.

  3. Push the commit and the tag:

    git push
    git push --tags
  4. Wait for CI to pass. Because of the git tag, the CI jobs will publish artifacts to a GitHub release. The npm module of tree-sitter-cli works by downloading the appropriate binary from the corresponding GitHub release during installation. So it’s best not to publish the npm package until the binaries are uploaded.

  5. Publish the npm package:

    cd cli/npm
    npm publish