All essentials

Drop a filled form and I'll lock the answers in.

Free tool

Flatten PDF Forms

Flatten the AcroForm fields in a PDF so the filled values become part of the page and can no longer be edited.

Good to know

  • Every field is listed with its type before anything is written.
  • Flattening covers AcroForm fields — other annotations and layers are left alone.
  • Flattened values cannot be edited again, so keep the filled original.

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.

  • No page grid is drawn, so file size binds rather than page count — comfortable to roughly 200 MB.
  • It is the number of form fields, not pages, that makes flattening slow; a long document with a handful of fields is quick.

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.