libfreeform

Parser for Apple Freeform pasteboard data — Rust core, WebAssembly bindings for Node, Bun, Deno, and browsers.

Freeform writes one selection in several parallel pasteboard flavors. This library snapshots every flavor, decodes supported tiers independently, and retains unknown records and bytes for newer decoders:

decodePasteboard returns a decoded, failed, or absent outcome for each independent tier. A damaged TSU manifest cannot discard valid native data; mismatched tiers are reported instead of partially joined. Private CRL formats remain OS-version fragile, so unsupported fields retain their bounded raw records rather than receiving guessed values. The wire formats are documented in docs/FORMAT.md.

Rust

cargo add libfreeform

use libfreeform::{
    FreeformBlobs, FreeformFlavor, FreeformTier, decode_pasteboard,
};

let flavors = [
    ("com.apple.drawing", "pb_dump/flavor-000003.bin"),
    (
        "com.apple.freeform.CRLNativeData",
        "pb_dump/flavor-000001.bin",
    ),
    (
        "com.apple.freeform.TSUDescription",
        "pb_dump/flavor-000002.bin",
    ),
]
.into_iter()
.filter_map(|(uti, path)| {
    std::fs::read(path)
        .ok()
        .map(|bytes| FreeformFlavor { uti: uti.into(), bytes })
})
.collect();

let decoded = decode_pasteboard(FreeformBlobs {
    change_count: None,
    flavors,
});

if let FreeformTier::Decoded(drawing) = decoded.drawing {
    for stroke in drawing.strokes {
        println!("{}: {} spline controls", stroke.ink_type, stroke.points.len());
    }
}
if let FreeformTier::Decoded(native) = decoded.native {
    for item in native.items {
        println!("{:?}: {:?}", item.class_name, item.kind);
    }
}

The optional serde feature derives Serialize/Deserialize (camelCase field names) on all decoded types. Full API docs: docs.rs/libfreeform.

JavaScript / TypeScript

npm install libfreeform   # or: bun add libfreeform

The package is a single ESM module backed by WebAssembly. The wasm initializes at import — no init call, no async ceremony:

import { decodePasteboard } from 'libfreeform';
import { readFileSync } from 'node:fs';

const bytes = path => new Uint8Array(readFileSync(path));
const decoded = decodePasteboard({
  flavors: [
    { uti: 'com.apple.drawing', bytes: bytes('pb_dump/flavor-000003.bin') },
    {
      uti: 'com.apple.freeform.CRLNativeData',
      bytes: bytes('pb_dump/flavor-000001.bin'),
    },
    {
      uti: 'com.apple.freeform.TSUDescription',
      bytes: bytes('pb_dump/flavor-000002.bin'),
    },
  ],
});

if (decoded.drawing.status === 'decoded') {
  console.log(decoded.drawing.value.strokes.length);
}
if (decoded.native.status === 'decoded') {
  console.log(decoded.native.value.items);
}

• Node ≥ 20 / Bun — works as-is (the node export condition loads the wasm synchronously from disk).
• Deno — deno add npm:libfreeform, then import as above; run with -R so the module may read its own .wasm file.
• Browsers via a bundler (Vite, webpack 5, Rollup) — works as-is; the wasm is referenced with the standard new URL(..., import.meta.url) asset pattern.
• Browsers via CDN — import { decodePasteboard } from 'https://esm.sh/libfreeform'.

Every function is fully typed (index.d.ts ships with the package); decoded objects use camelCase keys mirroring the Rust types.

JS API

Capturing pasteboard data

pbpaste only sees text. Copy something in Freeform, then capture one atomic snapshot:

swift tools/dump_pasteboard.swift pb_dump

The destination contains manifest.json plus collision-safe flavor-NNNNNN.bin files. The manifest preserves exact UTIs, ordering, byte counts, and the stable pasteboard changeCount; capture retries if the pasteboard changes and atomically replaces an older snapshot without stale conditional assets.

Stability

The com.apple.freeform.* formats are private and can change with any Freeform or OS update. CRL records are decoded only inside established object boundaries, and unknown fields remain available as raw bytes. FreeformCompatibility and per-tier failures let callers choose a render fallback without confusing absence, truncation, unsupported versions, or correlation failures.

Repository layout

• src/ — the parser (pure Rust rlib; published to crates.io)
• libfreeform-wasm/lib.rs — target-gated wasm-bindgen module; the same crate emits it as a cdylib for npm
• npm/ — the npm package: entry points, types, build script
• tests/ — cross-runtime smoke tests (Node, Bun, Deno, headless Chromium)
• docs/FORMAT.md — the reverse-engineered format documentation
• tools/dump_pasteboard.swift — pasteboard capture utility

Development

cargo test --all-features                  # Rust unit + fixture tests
cargo clippy --all-targets --all-features -- -D warnings
cargo +nightly fmt --all                   # rustfmt.toml uses nightly-only options
bunx @biomejs/biome check --write .        # JS/JSON lint + format
node npm/build.mjs                         # build the npm package into npm/dist
node tests/setup.mjs && node tests/smoke.mjs   # runtime smoke (also: bun/deno)

Building the npm package needs the wasm32-unknown-unknown target, a wasm-bindgen CLI matching the pin in root Cargo.toml, and optionally wasm-opt (binaryen). See RELEASING.md for the release process.

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.