pdf-lib
TypeScript-first PDF library for creating and modifying PDF documents in both Node.js and browsers. Unlike jsPDF (create-only) or pdf-parse (read-only), pdf-lib can both create new PDFs and modify existing ones — adding pages, filling form fields, embedding images, merging documents, and reading/writing metadata. Used for document workflows requiring PDF manipulation.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Local processing — no network risk. PDF content injection risk if processing untrusted PDFs — validate and sandbox PDF inputs in production. MIT licensed with no telemetry.
⚡ Reliability
Best When
You need to create or modify PDF documents programmatically — especially form filling, PDF merging, or adding content to existing PDFs.
Avoid When
You need HTML-to-PDF conversion, full-featured PDF text extraction, or legal digital signatures.
Use Cases
- • Fill PDF form fields programmatically in agent document processing workflows — employment forms, contracts, tax documents
- • Merge multiple PDFs into a single document in agent report generation pipelines
- • Add watermarks, stamps, or headers/footers to existing PDF documents in batch processing agents
- • Embed images and vector graphics into PDFs for certificate generation and branded document creation
- • Extract and manipulate PDF metadata (author, title, creation date) in document management agent workflows
Not For
- • HTML-to-PDF conversion — pdf-lib doesn't render HTML; use Puppeteer for that
- • PDF text extraction for analysis — use pdf-parse or PyMuPDF for text extraction; pdf-lib's text extraction is limited
- • Digital signature creation for legal compliance — PDF signing requires proper certificate authority chains beyond pdf-lib's scope
Interface
Authentication
No authentication — local library.
Pricing
MIT-licensed open source library. Actively maintained.
Agent Metadata
Known Gotchas
- ⚠ All operations are async (Promise-based) — must await PDFDocument.load(), embedFont(), save(); forgetting await produces empty or corrupt PDFs
- ⚠ Custom fonts must be embedded as ArrayBuffer — TTF/OTF font files must be read and embedded; system fonts are not available
- ⚠ PDF form filling requires knowing exact field names from the original PDF — use getForm().getFields() to discover field names before writing
- ⚠ Password-protected PDFs require the password at load time — pdf-lib can load encrypted PDFs but most encryption schemes require explicit password parameter
- ⚠ PDF modification of PDFs with complex features (JavaScript, 3D, multimedia) may strip those features on save — pdf-lib is not a full PDF-compliant editor
- ⚠ Large PDFs (100+ pages) can consume significant memory during processing — consider streaming approaches or page-by-page processing for large documents
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for pdf-lib.
Scores are editorial opinions as of 2026-03-06.