Bazel rules for TypeScript

This is the canonical ruleset for using Bazel for TypeScript, based on, and recommended for all new projects.

This is a high-performance alternative to the @bazel/typescript npm package from rules_nodejs. The ts_project rule here is identical to the one in rules_nodejs, making it easy to migrate. Since rules_js always runs tools from the bazel-out tree, rules_ts naturally fixes most usability bugs with rules_nodejs:

  • Freely mix generated *.ts and tsconfig.json files in the bazel-out tree with source files
  • Fixes the need for any rootDirs settings in tsconfig.json as reported in
  • "worker mode" for ts_project now shares workers across all targets, rather than requiring one worker pool per target

rules_ts is just a part of what Aspect provides:

Known issues:


From the release you wish to use: copy the WORKSPACE snippet into your WORKSPACE file.


There are a number of examples in the examples/ folder.

If you'd like an example added, you can file a Feature Request.


See the API documentation in the docs/ folder.

From a BUILD file

The most common use is with the ts_project macro which invokes the tsc CLI to transform source files like .ts files into outputs such as .js and .d.ts files.

We encourage you to read about the transpiler property which lets you use a faster tool like Babel or SWC to produce the .js files, so you don't have to wait for type-checking in your fast development loop.

In a macro

Many organizations set default values, so it's common to write a macro to wrap ts_project, then ensure that your developers load your macro rather than loading from @aspect_rules_ts directly.

BUILD file generation

Aspect provides an alpha preview of our TypeScript BUILD file generator as part of the Aspect CLI. Run aspect configure to create or update BUILD.bazel files as you edit TypeScript sources.

Advanced: custom rules

If you know how to write Bazel rules, you might find that ts_project doesn't do what you want.

One way to customize it is to peel off one layer of indirection, by calling the ts_project_rule directly. This bypasses our default setting logic, and also the validation program which checks that ts_project attributes are well-formed.

You can also write a custom rule from scratch. We expose helper functions from /ts/private in this repo. Be aware that these are not a public API, so you may have to account for breaking changes which aren't subject to our usual semver policy.