LibPDF

A modern PDF library for TypeScript. Parse, modify, and generate PDFs with a clean, intuitive API.

Beta Software: LibPDF is under active development and APIs may change between minor versions, but we use it in production at Documenso and consider it ready for real-world use.

Why LibPDF?

LibPDF was born from frustration. At Documenso, we found ourselves wrestling with the JavaScript PDF ecosystem:

• PDF.js is excellent for rendering, but it’s read-only
• pdf-lib has a great API, but chokes on slightly malformed documents
• pdfkit only generates, no parsing at all

We kept adding workarounds. A patch here for a malformed xref table. A hack there for an encrypted document. Eventually, we decided to build what we actually needed:

• Lenient like PDFBox and PDF.js: opens documents other libraries reject
• Intuitive like pdf-lib: clean, TypeScript-first API
• Complete: encryption, digital signatures, incremental saves, form filling

Features

Feature	Status	Notes
Parse any PDF	Yes	Graceful fallback for malformed documents
Create PDFs	Yes	From scratch or modify existing
Encryption	Yes	RC4, AES-128, AES-256 (R2-R6)
Digital Signatures	Yes	PAdES B-B, B-T, B-LT, B-LTA
Form Filling	Yes	Text, checkbox, radio, dropdown, signature
Form Flattening	Yes	Bake fields into page content
Merge & Split	Yes	Combine or extract pages
Attachments	Yes	Embed and extract files
Text Extraction	Yes	With position information
Font Embedding	Yes	TTF/OpenType with subsetting
Images	Yes	JPEG, PNG (with alpha)
Incremental Saves	Yes	Append changes, preserve signatures

Installation

npm install @libpdf/core
# or
bun add @libpdf/core

Quick Start

Parse an existing PDF

import { PDF } from "@libpdf/core";

const pdf = await PDF.load(bytes);
const pages = await pdf.getPages();

console.log(`${pages.length} pages`);

Open an encrypted PDF

const pdf = await PDF.load(bytes, { credentials: "password" });

Fill a form

const pdf = await PDF.load(bytes);
const form = await pdf.getForm();

form.fill({
name: "Jane Doe",
email: "jane@example.com",
agreed: true,
});

const filled = await pdf.save();

Sign a document

import { PDF, P12Signer } from "@libpdf/core";

const pdf = await PDF.load(bytes);
const signer = await P12Signer.create(p12Bytes, "password");

const signed = await pdf.sign({
signer,
reason: "I approve this document",
});

Merge PDFs

const merged = await PDF.merge([pdf1Bytes, pdf2Bytes, pdf3Bytes]);

Draw on a page

import { PDF, rgb } from "@libpdf/core";

const pdf = PDF.create();
const page = pdf.addPage({ size: "letter" });

page.drawText("Hello, World!", {
x: 50,
y: 700,
fontSize: 24,
color: rgb(0, 0, 0),
});

page.drawRectangle({
x: 50,
y: 600,
width: 200,
height: 100,
color: rgb(0.9, 0.9, 0.9),
borderColor: rgb(0, 0, 0),
borderWidth: 1,
});

const output = await pdf.save();

Runtime Support

LibPDF runs everywhere:

• Node.js 20+
• Bun
• Browsers (modern, with Web Crypto)

Known Limitations

Some features are not yet implemented:

Feature	Status	Notes
Signature verification	Not implemented	Signing works; verification is planned
TrueType Collections (.ttc)	Not supported	Extract individual fonts first
JBIG2 image decoding	Passthrough only	Images preserved but not decoded
JPEG2000 (JPX) decoding	Passthrough only	Images preserved but not decoded
Certificate encryption	Not supported	Password encryption works
JavaScript actions	Ignored	Form calculations not executed

These limitations are documented to set expectations. Most don’t affect typical use cases like form filling, signing, or document manipulation.

Philosophy

Be lenient

Real-world PDFs are messy. Export a document through three different tools and you’ll get three slightly different interpretations of the spec. LibPDF prioritizes opening your document over strict compliance. When standard parsing fails, we fall back to brute-force recovery, scanning the entire file to rebuild the structure.

Two API layers

• High-level: PDF, PDFPage, PDFForm for common tasks
• Low-level: PdfDict, PdfArray, PdfStream for full control

Documentation

Full documentation at libpdf.dev

Sponsors

LibPDF is developed by Documenso, the open-source DocuSign alternative.

Contributing

We welcome contributions! See our contributing guide for details.

# Clone the repo
git clone https://github.com/libpdf/core.git
cd libpdf

# Install dependencies
bun install

# Run tests
bun run test

# Type check
bun run typecheck

License

MIT

The src/fontbox/ directory is licensed under Apache-2.0 as it is derived from Apache PDFBox.