All essentials

Drop a PDF and I'll lay a watermark over it.

Free tool

Watermark PDF

Watermark a PDF with text or an image. Stamp CONFIDENTIAL across every page, or drop in your firm's logo and place it where you want.

Good to know

  • Text or image: type the wording, or drop a PNG or JPEG from your machine.
  • The watermark is drawn into the page, so it survives printing and re-saving.
  • It sits on top of the existing content — it does not hide or redact anything underneath.

Your files stay on your machine

This tool runs entirely inside your browser tab. Nothing is uploaded, stored, or sent to a server — close the tab and every trace is gone.

These are the free ones — see the full suite

How big a file can it take?

There is no upload, so there is no upload limit — but the work happens in this tab, which means your browser’s memory is the budget. Nothing here will refuse a file for being large; a big enough one simply gets slow and, eventually, reloads the tab. The figures below are rules of thumb on a desktop browser, not enforced caps. On a phone or tablet, expect a good deal less.

  • Pages are thumbnailed so you can place the mark, so page count binds — comfortable to around 500 pages, sluggish past 1,500.
  • A logo is embedded once and reused on every page, so a large PNG costs you its size once rather than per page.

Password-protected PDFs are declined whatever their size — unlock the file first. If a run does die on a long document, splitting it into volumes and working through them one at a time is the reliable way round it.

Built on open source

The Essentials tools do their work in your browser using these open-source libraries, used under the licenses below. Each remains the copyright of its authors.

  • pdf-libMIT · creates and edits the PDFs you download
  • pdf.jsApache-2.0 · reads your PDF and renders the page previews
  • SheetJS (xlsx)Apache-2.0 · reads Excel workbooks — .xlsx, .xls, .xlsb and .ods
  • hyparquetMIT · reads Apache Parquet files
  • hyparquet-compressorsMIT · the Parquet codecs beyond Snappy — Gzip, Zstd, Brotli, LZ4
  • JSZipMIT · bundles multi-file results into one ZIP
  • LucideISC · the icons throughout these tools
  • ReactMIT · the interface itself
  • Next.jsMIT · builds and serves these pages

pdf.js ships fallback fonts contributed by Foxit Software, redistributed here as part of pdf.js. JSZip is dual-licensed; it is used here under the MIT license.