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We welcome and appreciate all contributions to Deno.

This page serves as a helper to get you started on contributing.


There are numerous repositories in the denoland organization that are part of the Deno ecosystem.

Repositories have different scopes, use different programming languages and have varying difficulty level when it comes to contributions.

To help you decide which repository might be the best to start contributing (and/or falls into your interest), here's a short comparison (codebases primarily comprise the languages in bold):


This is the main repository that provides the deno CLI.

If you want to fix a bug or add a new feature to deno this is the repository you want to contribute to.

Some systems, including a large part of the Node.js compatibility layer are implemented in JavaScript and TypeScript modules. These are a good place to start if you are looking to make your first contribution.

While iterating on such modules it is recommended to include --features __runtime_js_sources in your cargo flags. This is a special development mode where the JS/TS sources are not included in the binary but read at runtime, meaning the binary will not have to be rebuilt if they are changed.

# cargo build
cargo build --features __runtime_js_sources

# cargo run -- run hello.ts
cargo run --features __runtime_js_sources -- run hello.ts

# cargo test integration::node_unit_tests::os_test
cargo test --features __runtime_js_sources integration::node_unit_tests::os_test

Also remember to reference this feature flag in your editor settings. For VSCode users, combine the following into your workspace file:

"settings": {
"rust-analyzer.cargo.features": ["__runtime_js_sources"]

Languages: Rust, JavaScript, TypeScript


The standard library for Deno.

Languages: TypeScript, WebAssembly


The next-gen web framework.

Languages: TypeScript, TSX


Linter that powers deno lint subcommand.

Languages: Rust


Documentation generator that powers deno doc subcommand and

Languages: Rust


Frontend for documentation generator:

Languages: TypeScript, TSX, CSS


Rust bindings for the V8 JavaScript engine. Very technical and low-level.

Languages: Rust


Library that provides bijection layer between V8 and Rust objects. Based on serde library. Very technical and low-level.

Languages: Rust


Official Docker images for Deno.

General remarks

  • Read the style guide.

  • Please don't make the benchmarks worse.

  • Ask for help in the community chat room.

  • If you are going to work on an issue, mention so in the issue's comments before you start working on the issue.

  • If you are going to work on a new feature, create an issue and discuss with other contributors before you start working on the feature; we appreciate all contributions but not all proposed features will be accepted. We don't want you to spend hours working on code that might not be accepted.

  • Please be professional in the forums. We follow Rust's code of conduct (CoC). Have a problem? Email

Submitting a pull request

Before submitting a PR to any of the repos, please make sure the following is done:

  1. Give the PR a descriptive title.

Examples of good PR title:

  • fix(std/http): Fix race condition in server
  • docs(console): Update docstrings
  • feat(doc): Handle nested re-exports

Examples of bad PR title:

  • fix #7123
  • update docs
  • fix bugs
  1. Ensure there is a related issue and that it is referenced in the PR text.
  2. Ensure there are tests that cover the changes.

Submitting a PR to deno

In addition to the above make sure that:

  1. cargo test passes - this will run full test suite for deno including unit tests, integration tests and Web Platform Tests

  2. Run ./tools/format.js - this will format all of the code to adhere to the consistent style in the repository

  3. Run ./tools/lint.js - this will check Rust and JavaScript code for common mistakes and errors using clippy (for Rust) and dlint (for JavaScript)

Submitting a PR to deno_std

In addition to the above make sure that:

  1. All of the code you wrote is in TypeScript (ie. don't use JavaScript)

  2. deno test --unstable --allow-all passes - this will run full test suite for the standard library

  3. Run deno fmt in the root of repository - this will format all of the code to adhere to the consistent style in the repository.

  4. Run deno lint - this will check TypeScript code for common mistakes and errors.

Submitting a PR to fresh

First, please be sure to install Puppeteer. Then, please ensure deno task ok is run and successfully passes.

Documenting APIs

It is important to document all public APIs and we want to do that inline with the code. This helps ensure that code and documentation are tightly coupled together.

JavaScript and TypeScript

All publicly exposed APIs and types, both via the deno module as well as the global/window namespace should have JSDoc documentation. This documentation is parsed and available to the TypeScript compiler, and therefore easy to provide further downstream. JSDoc blocks come just prior to the statement they apply to and are denoted by a leading /** before terminating with a */. For example:

/** A simple JSDoc comment */
export const FOO = "foo";

Find more at:


Use this guide for writing documentation comments in Rust code.