All essentials

Drop a PDF and I will squeeze the scans in it.

Free tool

Compress PDF

Reduce the size of a PDF by re-compressing the scans inside it, in your browser. Aim at a court's byte limit, or pick a setting. Selectable text, bookmarks and links stay intact — nothing is rasterised.

Good to know

  • Only images are re-encoded — text, bookmarks, links and form fields are never touched.
  • Aim at a limit — the same 10, 35 and 50 MB caps Split PDF by Size offers — and the gentlest setting that clears it is the one used.
  • Identical images repeated across pages, a letterhead or a logo, are collapsed onto one copy.
  • Bitonal fax scans, CMYK, indexed and JPEG 2000 images are left alone rather than guessed at.
  • Before you run it, the tool says how many images it found and how many are big enough to be worth re-encoding.
  • The result is checked against your original page for page and character for character before it is offered.

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.

  • One image is decoded at a time and released straight after, so it is the largest single scan that binds rather than the file — a 200 MB production of letter-size pages is comfortable.
  • Aiming at a tight limit can mean up to three full passes over the document, each re-reading every image; choosing “Just make it smaller” and naming the setting yourself runs exactly one.

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.