cupertino-filesPages, Numbers, and Keynote. In TypeScript.

Open, edit, and save Apple's document formats anywhere JavaScript runs. No Mac required. An open reverse-engineering, still under way — designed so every byte you don't touch comes back exactly.

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The format, documented

GitHub

A cardboard tray of apples, each wearing a cupertino-files fruit sticker

The whole stack, from hex

Snappy, protobuf, ZIP, IWA archives, the object graph — reimplemented by reading real documents until they made sense. A typed model on top, so you get to think in paragraphs and slides instead.

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Bytes in, bytes out

What you don't edit is left exactly alone — that's the design, held against every fixture we could legally get. Documents from app versions we haven't met yet should ride along unharmed.

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It mostly just works

And where it doesn't, it declines with a reason — a clear error beats a plausible guess. Password-protected documents are refused on principle.

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For the next implementer

The format written down as we learn it, a language-neutral conformance suite, and the recovered schemas with their provenance. Port it, check yourself, tell us what we got wrong.

Say hello

installyour first edit

npm install cupertino-files

import { readFileSync, writeFileSync } from "node:fs";
import { PagesDocument } from "cupertino-files";

const doc = PagesDocument.load(new Uint8Array(readFileSync("Report.pages")));

doc.appendParagraph("hello");   // the traditional first word
doc.replaceText("2024", "2025");
doc.sections()[0].setHeaderText("Confidential");

writeFileSync("Report 2025.pages", doc.save());

Open the result in Pages. It opens — and if yours ever doesn't, that is a bug report we genuinely want. (How we know it usually does.)

one more thing …

This isn't only a library. It's the format, written down: a specification measured from real documents, a conformance suite any implementation can test against, and the recovered schemas with their provenance. If you're building iWork support in another language — or another decade — the knowledge is yours too.