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To get TypeScript definitions for Bun’s built-in APIs, install @types/bun.
terminal
bun add -d @types/bun # dev dependency
You can now reference the Bun global in your TypeScript files without errors in your editor.

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Suggested compilerOptions

Bun supports top-level await, JSX, and imports with .ts extensions, which TypeScript doesn’t allow by default. Use these compilerOptions in a Bun project so TypeScript doesn’t warn about those features.
tsconfig.json
{
  "compilerOptions": {
    // Environment setup & latest features
    "lib": ["ESNext"],
    "target": "ESNext",
    "module": "Preserve",
    "moduleDetection": "force",
    "jsx": "react-jsx",
    "allowJs": true,
    "types": ["bun"],

    // Bundler mode
    "moduleResolution": "bundler",
    "allowImportingTsExtensions": true,
    "verbatimModuleSyntax": true,
    "noEmit": true,

    // Best practices
    "strict": true,
    "skipLibCheck": true,
    "noFallthroughCasesInSwitch": true,
    "noUncheckedIndexedAccess": true,
    "noImplicitOverride": true,

    // Some stricter flags (disabled by default)
    "noUnusedLocals": false,
    "noUnusedParameters": false,
    "noPropertyAccessFromIndexSignature": false
  }
}
Running bun init in a new directory generates this tsconfig.json for you.
terminal
bun init

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TypeScript 6 and 7

If you’re using TypeScript 6.0 or later, you also need "types": ["bun"] in your compilerOptions. See TypeScript 6 and 7.