Amber is not a drop-in Node.js replacement. Each module below is Stable only for the methods named in its contract. Everything else in src/nodejs_core/ is Preview. For a searchable view, use the compatibility page.

Modules and loading

API	Id	Notes
CommonJS `require`, `module.exports`, `require.resolve`, `createRequire`	G28 (provisional)	`node_modules` walk, `"exports"` / `"imports"` / `"main"`, JSON, TS, and ESM via `require`. No `require.cache`; resolve errors have no `code`.
`node:` and bare builtin names	G28	Loading a builtin does not make its whole API Stable.

File system and paths

API	Id	Notes
`fs`, `fs/promises`	G8, G77	Byte read and write, `mkdir`, `stat`, `copyFile`, `rm`, `realpath`, fds, `chmod`, `access`, `existsSync`, `readdir` dirents, system errors. `promises.open` returns a `FileHandle`. Async work runs on the isolate thread at the next tick.
`fs.watch`, `fs.watchFile`	G64 (tentative)	Real OS watcher and stat polling. No `fs.promises.watch`.
`fs.cp`, `fs.opendir`, `fs.statfs`	G76 (tentative)	Recursive copy, a `Dir` snapshot, and Unix `statfs`.
`path`	G17	POSIX semantics. `path.win32` only changes `sep` and `delimiter`.

fs.glob is not implemented.

Core utilities

API	Id	Notes
`events` (`EventEmitter`)	G18	No `events.on` async iterator.
`buffer` / `Buffer`	G19	`from`, `alloc`, `concat`, `byteLength`, `toString`, `slice`. `compare` and `readUInt*` are outside the pin.
`util`	G22, G59	`format`, shallow `inspect`, `promisify`, `callbackify`, `inherits`, listed `util.types`.
`process`	G22, G44, G53, G54, G70	`nextTick`, `env`, `cwd`, `pid`, `platform`, `stdout.write`, `hrtime`, `memoryUsage`, and `stdin` UTF-8 string chunks. Heap fields are estimates; `process.on` / `off` are no-ops and not Stable.
`os`	G20, G62, G63	Host info, `hostname`, real `networkInterfaces`.
`querystring`	G38	Fixed `&` and `=` separators.
`string_decoder`	G39, G68	UTF-8 plus latin1, ascii, base64, hex, utf16le. No `base64url`.
`assert`	G40, G69	`ok`, `strictEqual`, `deepStrictEqual`, `throws`, `match`, `rejects`, and a few more. Loose `equal` semantics are not pinned.
`timers`, `timers/promises`	G42, G50	Same functions as the globals; Promise `setTimeout` and `setImmediate` with `AbortSignal`.
`tty.isatty`	G49	Always `false` on Windows today.
`vm`	G55, G66 (tentative)	`runInThisContext` and `runInNewContext`. Not full Contextify.
`vm.createContext`	G73	`createContext` / `isContext` markers and `runInContext`. Persistent context reuse stays out.
`diagnostics_channel`	G56 (tentative)	`channel` pub/sub and `tracingChannel.traceSync`.
`async_hooks`	G57 (tentative)	`AsyncResource` and `AsyncLocalStorage`. No `createHook`.
`readline`	G46 (tentative)	`question()` on host stdin and stdout only.

Crypto and compression

API	Id	Notes
`crypto` hashes and random	G23	`createHash`, `createHmac` (md5, sha1, sha256, sha384, sha512, blake3), `randomBytes`, `randomUUID`, `timingSafeEqual`. Returns `Uint8Array`.
`crypto` AES ciphers	G43, G51, G52	`createCipheriv` / `createDecipheriv` for AES-CBC, AES-GCM, and AES-CTR.
`zlib`	G21, G48, G58	Sync and callback gzip, deflate, and raw deflate.

KDF, sign and verify, key pairs, KeyObject, brotli, and streaming createGzip are not Stable.

Processes and networking

API	Id	Notes
`child_process` sync	G25	`execSync`, `spawnSync`. `pid` is `0`.
`child_process` async	G47, G60, G67	`exec`, `execFile`, `spawn` with captured output, and `fork` with JSON IPC. No live stdio pipes.
`http` server	G37 (tentative)	`createServer`, `listen`, buffered responses, keep-alive.
`http` client	G72	`request` / `get`, one buffered HTTP/1.1 body. No `https`, Agent, or chunked streaming.
`perf_hooks`	G74	`performance`, `PerformanceObserver`, `timerify`.
`worker_threads`	G75	Real OS thread, JSON `postMessage`. No `transferList` or nested workers.
`net` server and client	G45, G61 (tentative)	`createServer` listen and accept; `net.connect` client.
`dns`	G27, G65	`lookup`, `resolve*`, `reverse`, `getServers` from the OS resolver.
`url`	G26	POSIX `fileURLToPath` and `pathToFileURL`. Legacy `parse` is outside.
`stream`	G24, G71	`Readable`, `Writable`, `PassThrough`, `Transform`, and callback `pipeline`. No `Duplex` or `stream/promises`.

Not supported

These fail or reject instead of pretending to work:

http.Agent, the https module, and http2.
Streaming zlib.createGzip family, brotli, and zlib.constants.
Node native addons beyond the Experimental N-API hello loader.

Conformance

The Node conformance scorecard in tests/conformance/ is 56/56 on main. See Stability levels for what that number does and does not mean.

Node.js compatibility