v0.25.6

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• Fix a memory leak when cancel() is used on a build context (#​4231)

  Calling rebuild() followed by cancel() in rapid succession could previously leak memory. The bundler uses a producer/consumer model internally, and the resource leak was caused by the consumer being termianted while there were still remaining unreceived results from a producer. To avoid the leak, the consumer now waits for all producers to finish before terminating.

• Support empty :is() and :where() syntax in CSS (#​4232)

  Previously using these selectors with esbuild would generate a warning. That warning has been removed in this release for these cases.

• Improve tree-shaking of try statements in dead code (#​4224)

  With this release, esbuild will now remove certain try statements if esbuild considers them to be within dead code (i.e. code that is known to not ever be evaluated). For example:

  // Original code
  return 'foo'
  try { return 'bar' } catch {}
  
  // Old output (with --minify)
  return"foo";try{return"bar"}catch{}
  
  // New output (with --minify)
  return"foo";

• Consider negated bigints to have no side effects

  While esbuild currently considers 1, -1, and 1n to all have no side effects, it didn't previously consider -1n to have no side effects. This is because esbuild does constant folding with numbers but not bigints. However, it meant that unused negative bigint constants were not tree-shaken. With this release, esbuild will now consider these expressions to also be side-effect free:

  // Original code
  let a = 1, b = -1, c = 1n, d = -1n
  
  // Old output (with --bundle --minify)
  (()=>{var n=-1n;})();
  
  // New output (with --bundle --minify)
  (()=>{})();

• Support a configurable delay in watch mode before rebuilding (#​3476, #​4178)

  The watch() API now takes a delay option that lets you add a delay (in milliseconds) before rebuilding when a change is detected in watch mode. If you use a tool that regenerates multiple source files very slowly, this should make it more likely that esbuild's watch mode won't generate a broken intermediate build before the successful final build. This option is also available via the CLI using the --watch-delay= flag.

  This should also help avoid confusion about the watch() API's options argument. It was previously empty to allow for future API expansion, which caused some people to think that the documentation was missing. It's no longer empty now that the watch() API has an option.

• Allow mixed array for entryPoints API option (#​4223)

  The TypeScript type definitions now allow you to pass a mixed array of both string literals and object literals to the entryPoints API option, such as ['foo.js', { out: 'lib', in: 'bar.js' }]. This was always possible to do in JavaScript but the TypeScript type definitions were previously too restrictive.

• Update Go from 1.23.8 to 1.23.10 (#​4204, #​4207)

  This should have no effect on existing code as this version change does not change Go's operating system support. It may remove certain false positive reports (specifically CVE-2025-4673 and CVE-2025-22874) from vulnerability scanners that only detect which version of the Go compiler esbuild uses.

• Experimental support for esbuild on OpenHarmony (#​4212)

  With this release, esbuild now publishes the @esbuild/openharmony-arm64 npm package for OpenHarmony. It contains a WebAssembly binary instead of a native binary because Go doesn't currently support OpenHarmony. Node does support it, however, so in theory esbuild should now work on OpenHarmony through WebAssembly.

  This change was contributed by @​hqzing.

v1.24.5

v0.7.19

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The uv build backend is now stable, and considered ready for production use.

The uv build backend is a great choice for pure Python projects. It has reasonable defaults, with the goal of requiring zero configuration for most users, but provides flexible configuration to accommodate most Python project structures. It integrates tightly with uv, to improve messaging and user experience. It validates project metadata and structures, preventing common mistakes. And, finally, it's very fast — uv sync on a new project (from uv init) is 10-30x faster than with other build backends.

To use uv as a build backend in an existing project, add uv_build to the [build-system] section in your pyproject.toml:

[build-system]
requires = ["uv_build>=0.7.19,<0.8.0"]
build-backend = "uv_build"

In a future release, it will replace hatchling as the default in uv init. As before, uv will remain compatible with all standards-compliant build backends.

Python

• Add PGO distributions of Python for aarch64 Linux, which are more optimized for better performance

See the python-build-standalone release for more details.

Enhancements

• Ignore Python patch version for --universal pip compile (#​14405)
• Update the tilde version specifier warning to include more context (#​14335)
• Clarify behavior and hint on tool install when no executables are available (#​14423)

Bug fixes

• Make project and interpreter lock acquisition non-fatal (#​14404)
• Includes sys.prefix in cached environment keys to avoid --with collisions across projects (#​14403)

Documentation

• Add a migration guide from pip to uv projects (#​12382)