Bun v1.3.3

Jarred Sumner · November 21, 2025

This release fixes 95 issues (addressing 348 👍 reactions)!

To install Bun

curl

npm

powershell

scoop

brew

docker

curl
curl -fsSL https://bun.sh/install | bash

npm
npm install -g bun

powershell
powershell -c "irm bun.sh/install.ps1|iex"

scoop
scoop install bun

brew
brew tap oven-sh/bun
brew install bun

docker
docker pull oven/bun
docker run --rm --init --ulimit memlock=-1:-1 oven/bun

To upgrade Bun

bun upgrade

CompressionStream and DecompressionStream

Bun now implements CompressionStream and DecompressionStream. These standard Web APIs allow for streaming compression and decompression of data without buffering the entire payload in memory.

In addition to the standard "gzip", "deflate", and "deflate-raw" formats, Bun also supports "brotli" and "zstd".

const response = await fetch("https://example.com");

// Compress the response body using gzip
const compressed = response.body.pipeThrough(new CompressionStream("gzip"));

// Or use zstd for faster compression
const zstd = response.body.pipeThrough(new CompressionStream("zstd"));

Thanks to @nektro for the contribution!

Control .env and bunfig.toml loading in standalone executables

Standalone executables created with bun build --compile normally look for .env and bunfig.toml files in the directory where the executable is run. You can now disable this behavior at build time using the --no-compile-autoload-dotenv and --no-compile-autoload-bunfig flags.

This is useful when you want to ensure the executable behaves deterministically, regardless of the configuration files present in the user's working directory.

# Disable .env and bunfig.toml loading
bun build --compile --no-compile-autoload-dotenv --no-compile-autoload-bunfig app.ts

You can also configure this via the JavaScript API:

await Bun.build({
  entrypoints: ["./app.ts"],
  compile: {
    // Disable .env loading
    autoloadDotenv: false,

    // Disable bunfig.toml loading
    autoloadBunfig: false,
  },
});

`retry` and `repeats` in `bun:test`

You can now use the retry and repeats options in bun:test. retry runs the callback function up to the specified number of times and if the test passes once then the test passes, while repeats runs the callback function up to the specified number of times and if the test fails once then the test fails. This is useful for handling flaky tests.

import { test } from "bun:test";

test(
  "flaky test",
  () => {
    if (Math.random() > 0.1) throw new Error("fail");
  },
  { retry: 3 },
);

test(
  "check for flakiness",
  () => {
    // run this 20 times to ensure it's stable
  },
  { repeats: 20 },
);

Thanks to @pfgithub for the contribution!

--no-env-file

You can now disable Bun's automatic .env file loading using the --no-env-file flag. This is useful in production environments or CI/CD pipelines where you want to rely solely on system environment variables.

bun run --no-env-file index.ts

This can also be configured in bunfig.toml:

# Disable loading .env files
env = false

Explicitly provided environment files via --env-file will still be loaded even when default loading is disabled.

SQLite 3.51.0

bun:sqlite has been updated to SQLite v3.51.0.

import { Database } from "bun:sqlite";

const db = new Database();
console.log(db.prepare("SELECT sqlite_version()").get());
// { "sqlite_version()": "3.51.0" }

Internal: Upgraded to Zig 0.15.2

Bun is now built with Zig 0.15.2. This reduces the binary size by 0.8MB and improves build times for contributors.

Bundler fixes

Fixed: A rare panic in the dev server when processing CSS assets in the incremental graph
Fixed: A rare panic in the dev server that could occur when a file referenced by a dynamic import is deleted during a reload

bun install fixes

Fixed: A rare crash during bun install involving optional peer dependencies
Fixed: A regression in bun install when parsing git dependency URLs with a leading hash
Fixed: A regression from Bun v1.3.2 that could cause bun ls --all with unresolved optional peer dependencies to crash
Fixed: A regression from Bun v1.3.2 where sharp versions older than v0.33.0 failed to install correctly

Windows fixes

Fixed: process.stdout now emits 'resize' events and SIGWINCH signals on Windows, which fixes terminal resizing issues in Claude Code & OpenCode on Windows
Improved: bun getcompletes works on Windows
Fixed: a crash on Windows when laptop hibernates and then wakes up and resumes execution after a Worker thread had been terminated

Node.js compatibility improvements

Implemented: _handle.fd in node:net and node:tls for better compatibility with libraries that rely on the socket file descriptor
Fixed: N-API bug preventing rspack or rsbuild from working

Web APIs fixes

Fixed: fuzzer-discovered crash when using JSON.stringify on a FormData object in rare cases
Fixed: fuzzer-discovered crash when calling stream on a Blob in certain edge cases
Fixed: sanitizer-discovered memory leak in Blob

Bun.serve

Fixed: An issue where Unicode characters in Bun.serve static Response objects given a string as input were missing the Content-Type header

Networking

Fixed: sanitizer-discovered memory leak in node:net.SocketAddress when passing an invalid port
Fixed: sanitizer-discovered memory leak in Bun.listen when errors are thrown during socket creation

YAML

Fixed: Bun.YAML.stringify would incorrectly serialize strings with leading zeros as numbers
Fixed: A performance issue where YAML merge keys could cause parsing to hang due to exponential complexity

Transpiler

Fixed: fuzzer-discovered crash in new Bun.Transpiler() with invalid configuration

Bun.spawn

Fixed: A small memory leak in Bun.spawn when passing extra non-IPC, non-stdout, non-stderr, and non-stdin file descriptors

TypeScript definitions

Fixed: Added JSDoc documentation for configVersion in BunLockFile type definition
Fixed: Added missing "css", "jsonc", "yaml", and "html" to the Loader type definition
Fixed: Removed unnecessary dependency on @types/react in @types/bun

Security

Fixed: Updated root certificates to Mozilla NSS 3.117

bun upgrade fixes

Improved: bun upgrade now displays download sizes in human-readable units (e.g. 23.2MiB) instead of raw bytes

Bun v1.3.3

To install Bun

To upgrade Bun

Bun v1.3.2