Overlay text like 'CONFIDENTIAL' or 'DRAFT' across every page.
All processing happens in your browser — files never upload anywhere.
Add Watermark is a browser-based PDF utility powered by pdf-lib (a mature MIT-licensed WebAssembly PDF library). Drop your PDF, run the operation, and download the result — all without uploading. Because there's no server round-trip, Add Watermark is instantly available offline once the page has loaded.
pdf-lib (WASM PDF authoring / editing)
Every step runs on your device — nothing is uploaded.
Open Add Watermark on Toolspace.
Drop your PDF into the drop zone. It stays in your browser — no upload.
Adjust any settings shown (pages, quality, output naming).
Click the action button to process and download the result.
Add Watermark is powered by pdf-lib, a mature MIT-licensed PDF library compiled to WebAssembly. When you drop a PDF, it's parsed in-browser using pdf-lib's structured document model — no server round-trip, no upload, no telemetry. The output is a fresh PDF written using the ISO 32000-1 spec.
Add Watermark can open encrypted PDFs and watermark them if you have permission. If a PDF has an owner password (edit/copy restrictions), pdf-lib respects those flags but our PDF Unlock tool can remove them if you own the file.
Add Watermark handles PDFs up to about 500 MB smoothly on a modern laptop. Above that, you may hit browser memory limits — the fix is to close other tabs or split the PDF into chunks first.
Yes. pdf-lib preserves the PDF's object graph including AcroForm fields, page annotations, and outlines. Some heavily-optimized commercial PDFs (with unusual compression) may need to be re-saved once to normalize before editing.
Add Watermark processes one PDF per run to keep memory usage predictable. To batch, keep the tab open and drop PDFs one after another. Because there's no upload step, each run is instant.
No — Toolspace has no upload endpoint for Add Watermark. Your PDF is read into browser memory, processed by pdf-lib, and either downloaded back to your device or discarded when you close the tab.
All free, all browser-based, all zero-signup.