Bun v1.4.3

To install Bun

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

bun check: a TypeScript type checker built into Bun#

bun check is an incredibly fast TypeScript type checker that passes 100% of TypeScript 7.0.2's conformance test suite.

bun check

1 | import { greet } from "./user";
2 |
3 | const message = greet({ id: "1", name: "Ada" });
^
error: TS2322: Type 'string' is not assignable to type 'number'.
at src/index.ts:3:25

Found 1 error in 1 file, checked 2 files [14.00ms]

It's 3x to 6.4x faster than tsc 7.0.2, on a 16-core Apple silicon Mac:

And it uses 2.2x to 4.9x less memory:

It's a port of typescript-go. It reads your tsconfig.json, reports the same errors as tsc, and uses every CPU core. You don't need the typescript package installed.

It only type checks. It doesn't emit JavaScript or .d.ts files, and there's no language server, so your editor keeps using TypeScript.

bun run --check#

Type check, then run. If there's a type error, your code doesn't run.

bun run --check src/index.ts

1 | import { greet } from "./user";
2 |
3 | console.log(greet({ id: "1", name: "Ada" }));
^
error: TS2322: Type 'string' is not assignable to type 'number'.
at src/index.ts:3:21

2 |   id: number;
^
note: The expected type comes from property 'id' which is declared here on type 'User'
at src/user.ts:2:3

Found 1 error in 1 file, checked 2 files [24.00ms]

It also works with package.json scripts (bun run --check dev) and with --watch, which checks again before every restart.

bun test --check#

Type check the test files and everything they import, then run the tests. If there's a type error, no tests run.

bun test --check

bun test v1.4.3
4 | test("greet", () => {
5 |   expect(greet({ id: "1", name: "Ada" })).toBe("hello Ada");
^
error: TS2322: Type 'string' is not assignable to type 'number'.
at src/user.test.ts:5:18

2 |   id: number;
^
note: The expected type comes from property 'id' which is declared here on type 'User'
at src/user.ts:2:3

Found 1 error in 1 file, checked 2 files [23.94ms]

bun build --check#

Type check, then bundle. A type error fails the build like any other build error, and nothing is written.

bun build --check ./src/index.ts --outdir out

3 | console.log(greet({ id: "1", name: "Ada" }));
^
error: TS2322: Type 'string' is not assignable to type 'number'.
at /app/src/index.ts:3:21

2 |   id: number;
^
note: TS6500: The expected type comes from property 'id' which is declared here on type 'User'
at /app/src/user.ts:2:3

Bun.build takes check: true.

Testing bun check#

Every commit of Bun runs TypeScript 7.0.2's complete conformance test suite (and we will continue to keep it up-to-date as TypeScript itself updates).

72 misconfigured open-source projects

For a project as complex as a TypeScript type checker, conformance tests aren't enough, so we deliberately misconfigured 72 popular open-source repositories and compared bun check's output with tsc's output.

Missing node_modules, mismatched TypeScript versions, no build step. Every error has to match: same file, line, column and error code.

The one mismatch is in vuejs/core. tsc only reports that error when global.ts comes before model.ts in files.

We ran 69 of them again under 11 other sets of compiler options:

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原文：Bun Blog｜Bun v1.4.3，2026-10-10