@thinkthinksyn/pdfcpu-wasm

Standalone npm package for the pdfcpu WebAssembly build. It exposes the full pdfcpu API (validate, optimize, merge, split, encrypt, watermark, extract, etc.) to TypeScript/JavaScript, entirely in-memory.

Install

npm install @thinkthinksyn/pdfcpu-wasm

Usage

import { Pdfcpu } from "@thinkthinksyn/pdfcpu-wasm/pdfcpu.ts";

const pdfcpu = await Pdfcpu.create("/pdfcpu.wasm");

const pdf = new Uint8Array(await (await fetch("doc.pdf")).arrayBuffer());

const opt = pdfcpu.optimize(pdf);
if (opt.ok) {
  // opt.data is a Uint8Array with the optimized PDF
}

See example/optimize.ts for a complete Deno/Node example.

Build locally

# Requires Go 1.25+
./build.sh

Output lands in dist/:

| File | Purpose | |---|---| | pdfcpu.wasm | Compiled WASM binary (~19 MB / ~5 MB gzip'd) | | wasm_exec.js | Go WASM runtime glue | | version.json | pdfcpu dependency version and build metadata |

Automated upstream updates

.github/workflows/update.yml runs daily and on manual dispatch. It:

1. Queries the latest stable release of pdfcpu/pdfcpu
2. Compares it with the version currently packaged
3. If newer, bumps go.mod / go.sum
4. Rebuilds the WASM binary
5. Bumps package.json version to match the upstream release
6. Publishes @thinkthinksyn/pdfcpu-wasm to npm
7. Commits the updated files back to this repo

Setup

1. Create the npm package @thinkthinksyn/pdfcpu-wasm at https://www.npmjs.com/.
2. Add an NPM_TOKEN secret to this repo:
   • Generate a Granular Access Token with Read and write access to @thinkthinksyn/pdfcpu-wasm and Bypass two-factor authentication enabled.
   • Add it at Settings → Secrets and variables → Actions → New repository secret.
3. Make sure the default GITHUB_TOKEN has Read and write permissions (Settings → Actions → General → Workflow permissions).

Manual run

gh workflow run update.yml -f pdfcpu_version=v0.13.0 -f dry_run=true

This checks out the specified upstream version, builds the WASM, but skips npm publish and the git push.

Repo layout

.
├── .github/workflows/update.yml   # Upstream update automation
├── main.go                         # Go WASM entry point
├── pdfcpu.ts                       # TypeScript bindings
├── build.sh                        # Local build script
├── package.json                    # npm metadata
├── go.mod / go.sum                 # Go module files
├── dist/                           # Build output (tracked for npm/distribution)
└── example/optimize.ts             # Usage example

License

Apache-2.0 (same as pdfcpu).