Compress PDF
Re-encodes pages as compressed JPEG images to reduce file size. Best for scanned or image-heavy PDFs.
- Browser-only
- No upload
- No login
- No watermark
- Clear instantly
- Open-source engines
Heads upWorks best for image-heavy PDFs (scans, photos). Text-only PDFs may not shrink much.
Drop files here
or use the buttons below · .pdf
Your file stays on this device · conversion runs locally in your browser
Deep dive
What is Compress PDF?
Compressing a PDF reduces its file size so it is easier to email, upload, or archive. Most size in a PDF comes from embedded images, so re-encoding those pages as compressed JPEGs is the most effective way to shrink a document.
FormatSwitch's Compress PDF tool rasterises each page in your browser, re-encodes it as a compressed JPEG, and rebuilds a lighter PDF. Because it runs locally there is no upload limit and no signup — even a scanned book can be compressed without leaving your device.
When to use it
- Shrink an email attachment under a provider's size limit.
- Reduce a scanned PDF from tens of megabytes to a few.
- Prepare a portfolio or resume PDF for online applications.
- Save storage space when archiving many PDFs.
How to use it safely without uploading
Drop your PDF and pick a quality preset — Small, Balanced, or High. The tool re-encodes each page locally and hands back a compressed PDF. Text-only PDFs may compress less than image-heavy scans.
Browser-based vs server-based conversion
Most online converters upload your files to their servers, process them there, and then let you download the result. That means your file exists on someone else's computer, often in logs and backups, sometimes indefinitely. FormatSwitch is different: every conversion runs on your device using WebAssembly and the browser's built-in Canvas and PDF engines. Your file never leaves your computer, so there is nothing to leak, nothing to subpoena, and nothing to trust us on — the code that does the work is running right in your tab.
FAQ
Compress PDF — questions people ask
- Can I compress a PDF privately without upload?
- No. Files are processed entirely in your browser using WebAssembly and the Canvas API. Nothing is uploaded to a server, and no copy is kept once you close or refresh the tab.
- How much smaller will my PDF be?
- Scanned and image-heavy PDFs typically shrink 40–80%. Vector or text-only PDFs shrink less because they are already small.
- Does the compressed PDF have a watermark?
- Never. FormatSwitch adds no watermark, logo, or quality cap to your output — the file you download is only what your browser produced.
- Are files stored anywhere?
- No. Files live only in your browser's memory (JavaScript heap). They disappear when you clear the queue, refresh, or close the tab. There is no server, no database, no log.
- Does it work on mobile?
- Yes. Every tool runs on modern iOS Safari and Android Chrome. Very large files may be slower on mobile because of tighter memory limits.
- Does the compressed PDF keep the original filename?
- Yes. Each output keeps the original filename with a short suffix (for example `-compressed` or `-converted`) so a whole folder of files stays recognisable after conversion.
- Can I use it offline?
- Yes, after the first visit. FormatSwitch is a Progressive Web App — the tool scripts are cached by your browser, so you can open the same tool later and use it without an internet connection.