Portable

Web-standard building blocks for any JavaScript runtime.

The web's missing standard library: fast, lightweight, composable packages, so you can write your code once and run it in browsers, Cloudflare Workers, Node 24+, Bun, and Deno.

Examples

Save a streamed OpenAI chat completion to a file as JSON Lines:

import * as Jsonl from '@portable/jsonl';
import * as Sse from '@portable/sse';
import * as Streams from '@portable/streams';

const response = await fetch('https://api.openai.com/v1/chat/completions', {
  method: 'POST',
  headers: { authorization: `Bearer ${apiKey}`, 'content-type': 'application/json' },
  body: JSON.stringify({ model, messages, stream: true }),
});
// `transcript` is a WritableStream<Uint8Array> that writes to a file.
await response.body!
  .pipeThrough(new Sse.DecoderStream())
  .pipeThrough(Streams.filter((event) => event.data !== '[DONE]'))
  .pipeThrough(Streams.map((event) => JSON.parse(event.data)))
  .pipeThrough(new Jsonl.EncoderStream())
  .pipeTo(transcript);

Strip photo metadata (GPS, camera, dates) before uploading:

import * as Exif from '@portable/exif';
import * as ImageSize from '@portable/image-size';

// `file` is a JPEG, PNG or WebP File from a file input or a drop.
const photo = Exif.strip(new Uint8Array(await file.arrayBuffer()));
const { width, height } = ImageSize.parse(photo);
await fetch(`/upload?width=${width}&height=${height}`, { method: 'POST', body: photo });

Packages

How the packages work

Every package follows the same conventions, so once you've used one, you know how the others work:

• Import a package as a namespace, such as import * as Csv from '@portable/csv', and call Csv.decode or new Csv.DecoderStream().
• Bytes go in and come out as Uint8Array, and a Node Buffer is accepted. Functions that take text also take its bytes.
• A streaming transform is a TransformStream that you pass to pipeThrough, as with TextDecoderStream.
• Every async function and every stream takes a signal. Aborting it stops the fetch calls, timers, and nested streams underneath, and the call rejects with signal.reason, as fetch does.
• An object that stays open, such as an SMTP client, a queue, or a WebSocket, has a close() method, a signal option that closes it, or both. It works with await using where the runtime has Symbol.asyncDispose.
• Options that take a time, such as now, accept a Date, or a Temporal.Instant. Times in results are Date objects.
• Errors extend the classes in @portable/errors. InvalidInputError means the data was malformed, and TypeError or RangeError means an argument was wrong.

Runtimes

The tests run in Chromium, Firefox, WebKit, Node 24, Node 26, Bun, and Deno. A check of every package also runs in workerd, the Cloudflare Workers runtime. Every package runs in Chrome 116, Firefox 124, and Safari 17.4 or later. Ed25519 signatures, in @portable/web-crypto, @portable/dkim, @portable/arc, and @portable/mail-auth, need Chrome 137 and Firefox 129, and X25519 keys in @portable/web-crypto need Chrome 133 and Firefox 130. @portable/smtp and @portable/sockets need a TCP socket API, so they run in Workers, Node, Bun, and Deno but not in browsers. The packages don't include polyfills, so if you support older browsers, you'll need to add them yourself.

License

MIT