Every day, Bun gets closer to 100% Node.js API compatibility. Today, popular frameworks like Next.js, Express, and millions ofnpm packages intended for Node just work with Bun. To ensure compatibility, we run thousands of tests from Node.js' test suite before every release of Bun.

If a package works in Node.js but doesn't work in Bun, we consider it a bug in Bun. Please open an issue and we'll fix it.

This page is updated regularly to reflect compatibility status of the latest version of Bun. The information below reflects Bun's compatibility withNode.js v23.

Built-in Node.js modules

`node:assert`

🟢 Fully implemented.

`node:buffer`

🟢 Fully implemented.

`node:console`

🟢 Fully implemented.

`node:dgram`

🟢 Fully implemented. > 90% of Node.js's test suite passes.

`node:diagnostics_channel`

🟢 Fully implemented.

`node:dns`

🟢 Fully implemented. > 90% of Node.js's test suite passes.

`node:events`

🟢 Fully implemented.EventEmitterAsyncResource usesAsyncResource underneath. 100% of Node.js's test suite for EventEmitter passes.

`node:fs`

🟢 Fully implemented. 92% of Node.js's test suite passes.

`node:http`

🟢 Fully implemented. Outgoing client request body is currently buffered instead of streamed.

`node:https`

🟢 APIs are implemented, butAgent is not always used yet.

`node:os`

🟢 Fully implemented. 100% of Node.js's test suite passes.

`node:path`

🟢 Fully implemented. 100% of Node.js's test suite passes.

`node:punycode`

🟢 Fully implemented. 100% of Node.js's test suite passes,deprecated by Node.js.

`node:querystring`

🟢 Fully implemented. 100% of Node.js's test suite passes.

`node:readline`

🟢 Fully implemented.

`node:stream`

🟢 Fully implemented.

`node:string_decoder`

🟢 Fully implemented. 100% of Node.js's test suite passes.

`node:timers`

🟢 Recommended to use globalsetTimeout, et. al. instead.

`node:tty`

🟢 Fully implemented.

`node:url`

🟢 Fully implemented.

`node:zlib`

🟢 Fully implemented. 98% of Node.js's test suite passes.

`node:async_hooks`

🟡AsyncLocalStorage, andAsyncResource are implemented. v8 promise hooks are not called, and its usage isstrongly discouraged.

`node:child_process`

🟡 Missingproc.gidproc.uid.Stream class not exported. IPC cannot send socket handles. Node.js <> Bun IPC can be used with JSON serialization.

`node:cluster`

🟡 Handles and file descriptors cannot be passed between workers, which means load-balancing HTTP requests across processes is only supported on Linux at this time (viaSO_REUSEPORT). Otherwise, implemented but not battle-tested.

`node:crypto`

🟡 MissingsecureHeapUsedsetEnginesetFips

Some methods are not optimized yet.

`node:domain`

🟡 MissingDomainactive

`node:http2`

🟡 Client & server are implemented (95.25% of gRPC's test suite passes). Missingoptions.allowHTTP1,options.enableConnectProtocol, ALTSVC extension, andhttp2stream.pushStream.

`node:module`

🟡 MissingsyncBuiltinESMExports,Module#load(). Overridingrequire.cache is supported for ESM & CJS modules.module._extensions,module._pathCache,module._cache are no-ops.module.register is not implemented and we recommend using aBun.plugin in the meantime.

`node:net`

🟡SocketAddress class not exposed (but implemented).BlockList exists but is a no-op.

`node:perf_hooks`

🟡 MissingcreateHistogrammonitorEventLoopDelay. It's recommended to useperformance global instead ofperf_hooks.performance.

`node:process`

🟡 Seeprocess Global.

`node:sys`

🟡 Seenode:util.

`node:tls`

🟡 Missingtls.createSecurePair.

`node:util`

🟡 MissinggetCallSitegetCallSitesgetSystemErrorMapgetSystemErrorMessagetransferableAbortSignaltransferableAbortControllerMIMETypeMIMEParams

`node:v8`

🟡writeHeapSnapshot andgetHeapSnapshot are implemented.serialize anddeserialize use JavaScriptCore's wire format instead of V8's. Other methods are not implemented. For profiling, usebun:jsc instead.

`node:vm`

🟡 Core functionality works, but experimental VM ES modules are not implemented, includingvm.Module,vm.SourceTextModule,vm.SyntheticModule,importModuleDynamically, andvm.measureMemory. Options liketimeout,breakOnSigint,cachedData are not implemented yet.

`node:wasi`

🟡 Partially implemented.

`node:worker_threads`

🟡Worker doesn't support the following options:stdinstdoutstderrtrackedUnmanagedFdsresourceLimits. MissingmarkAsUntransferablemoveMessagePortToContextgetHeapSnapshot.

`node:inspector`

🔴 Not implemented.

`node:repl`

🔴 Not implemented.

`node:sqlite`

🔴 Not implemented.

`node:test`

🟡 Partly implemented. Missing mocks, snapshots, timers. Usebun:test instead.

`node:trace_events`

🔴 Not implemented.

Node.js globals

The table below lists all globals implemented by Node.js and Bun's current compatibility status.

`AbortController`

🟢 Fully implemented.

`AbortSignal`

🟢 Fully implemented.

`Blob`

🟢 Fully implemented.

`Buffer`

🟢 Fully implemented.

`ByteLengthQueuingStrategy`

🟢 Fully implemented.

`__dirname`

🟢 Fully implemented.

`__filename`

🟢 Fully implemented.

`atob()`

🟢 Fully implemented.

`BroadcastChannel`

🟢 Fully implemented.

`btoa()`

🟢 Fully implemented.

`clearImmediate()`

🟢 Fully implemented.

`clearInterval()`

🟢 Fully implemented.

`clearTimeout()`

🟢 Fully implemented.

`CompressionStream`

🔴 Not implemented.

`console`

🟢 Fully implemented.

`CountQueuingStrategy`

🟢 Fully implemented.

`Crypto`

🟢 Fully implemented.

`SubtleCrypto (crypto)`

🟢 Fully implemented.

`CryptoKey`

🟢 Fully implemented.

`CustomEvent`

🟢 Fully implemented.

`DecompressionStream`

🔴 Not implemented.

`Event`

🟢 Fully implemented.

`EventTarget`

🟢 Fully implemented.

`exports`

🟢 Fully implemented.

`fetch`

🟢 Fully implemented.

`FormData`

🟢 Fully implemented.

`global`

🟢 Implemented. This is an object containing all objects in the global namespace. It's rarely referenced directly, as its contents are available without an additional prefix, e.g.__dirname instead ofglobal.__dirname.

`globalThis`

🟢 Aliases toglobal.

`Headers`

🟢 Fully implemented.

`MessageChannel`

🟢 Fully implemented.

`MessageEvent`

🟢 Fully implemented.

`MessagePort`

🟢 Fully implemented.

`module`

🟢 Fully implemented.

`PerformanceEntry`

🟢 Fully implemented.

`PerformanceMark`

🟢 Fully implemented.

`PerformanceMeasure`

🟢 Fully implemented.

`PerformanceObserver`

🟢 Fully implemented.

`PerformanceObserverEntryList`

🟢 Fully implemented.

`PerformanceResourceTiming`

🟢 Fully implemented.

`performance`

🟢 Fully implemented.

`process`

🟡 Mostly implemented.process.binding (internal Node.js bindings some packages rely on) is partially implemented.process.title is currently a no-op on macOS & Linux.getActiveResourcesInfosetActiveResourcesInfo,getActiveResources andsetSourceMapsEnabled are stubs. Newer APIs likeprocess.loadEnvFile andprocess.getBuiltinModule are not implemented yet.

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