How to compress a PDF (in your browser, not on a server)
- Drop a PDF onto the box above. The file is read locally by JavaScript — no network request happens.
- Pick a level. Recommended downsamples big embedded images to ~150 dpi, usually cutting 60–90% of the size while text stays selectable and sharp.
- Click Compress and download your smaller PDF. Still too big? Run the High level on the result.
Under the hood this page loads Ghostscript — the open-source PDF engine behind many desktop tools — compiled to WebAssembly. It writes the same -sDEVICE=pdfwrite -dPDFSETTINGS pipeline you would run on a command line, right here on your device.
Why "no upload" matters for PDFs
Contracts, résumés, medical reports, bank statements: these are exactly the files people want to shrink — and exactly the files they should not be handing to a random server. Cloud compressors promise to delete your file after an hour; a local compressor never had it in the first place.
- No TLS-then-delete policy to trust — the file never leaves your device.
- No account, no quota, no watermark, no "upload failed" round trips.
- Close the tab and there is nothing to erase anywhere. The engine is cached; your document is not.
Which compression level should I choose?
| Goal | Level | What it does |
|---|---|---|
| Email attachment under 10/25 MB, upload portal under 1–2 MB | High (~72 dpi) | Aggressive image downsampling; fine for on-screen reading, soft for print. |
| Everyday: sharing, submitting, archiving | Recommended (~150 dpi) | Looks crisp on screens and in normal printing; the biggest size drop for the quality. |
| Print-safe, photo-heavy keep-quality | Best (~300 dpi) | Mild recompression; use when the document must stay high-resolution. |
Frequently asked questions
How can I compress a PDF without uploading it to a website?
This tool runs Ghostscript compiled to WebAssembly inside your browser. The file is read locally by JavaScript, compressed in a worker thread on your own device, and handed back as a download — it is never sent over the network.
Will compressing reduce the quality of my PDF?
Only embedded images get downsampled; text and vector graphics stay selectable and sharp. Recommended (~150 dpi) looks crisp on screen and in normal printing. If you must keep print quality, pick Best.
How do I compress a PDF to 1MB (or 500KB) for an application portal?
Start with Recommended. If the output is still above your limit, compress the result again with High. Photo-heavy PDFs typically drop 60–90%.
Why didn't my PDF get smaller?
Some PDFs are already optimized — images are low-resolution and streams are well compressed. This page detects that and tells you instead of handing you a bigger file. Try the High level for a more aggressive pass.
Does it work on iPhone, Mac and Windows? Do I need to install anything?
Yes, in any recent browser — Chrome, Edge, Firefox or Safari 15+. No installation, no app, nothing to sign up for.
Is it really free and unlimited?
Yes: no account, no daily quota, no watermark. Because compression happens on your device, there is no server cost to ration.
Can I compress password-protected PDFs?
Not directly — open the file in your PDF reader first, remove the password, save a copy, then compress that copy (remember: all of this stays on your device).