PDF Compressor
Shrink a PDF without uploading it. Compression runs on your own machine.
Drop PDF files here
or
Supported formats: .pdf — multiple files supported
Why Your PDF Is Too Big
Almost always, it's the images. A page of plain text costs a few kilobytes. A page scanned at 300 DPI costs one to three megabytes, so a 20-page scanned contract lands somewhere around 30 MB — past Gmail's 25 MB attachment ceiling and past the upload cap on most government and job-application portals. Compression works by re-encoding those embedded images, which is why the same setting can cut one file by 80% and barely touch another.
The other online compressors send your file to a server, compress it there, and promise to delete it afterwards. This one has nowhere to send it. The compression code runs inside the browser tab through WebAssembly, on your own processor, so a signed contract or a medical scan never becomes someone else's log entry.
Pick Standard unless you have a reason not to. It re-encodes the images and leaves text selectable and searchable, which matters if anyone downstream needs to copy a clause or run a search. Drop several files in at once and take them back as a ZIP.
Compressing a PDF
- Drop your PDFs onto the page, or click to pick them
- Choose a level — Standard is the right default
- Hit Start Compression and watch the size drop
- Save the files one by one, or grab them all as a ZIP
What You Get
- Nothing is uploaded. The file is opened, compressed, and saved by your own browser
- Three levels, so you can trade quality against size deliberately
- Queue up a batch instead of doing one file at a time
- No file size cap from us — your device's memory is the only limit
- Advanced controls for image quality, DPI, and stripping metadata
- Works the same on a phone browser as on a desktop
- Free, unlimited, and there is no account to create
Why PDF Compressor on sakutto is safe
Many online tools upload your files to external servers for processing. This tool never sends your PDF files to any server — everything is processed entirely in your browser.
* Some AI-powered tools require server-side processing. Tools that send data to a server will always notify you beforehand.
| Comparison | Typical online tools | sakutto |
|---|---|---|
| Where data is sent | Uploaded to external servers | Nowhere — processed in your browser |
| Data leak risk | Risk during transfer and server storage | No risk — no network transfer occurs |
| External traffic | File data travels over the internet | No file data appears in network logs |
| Offline use | Not possible (server required) | Works offline after initial load |
How browser-based processing works
- WebAssembly (WASM): Processes PDF files in your browser at near-native speed. No server communication occurs.
- Web Workers: Runs on a background thread separate from the main thread, so your browser stays responsive during processing.
- After processing, your browser automatically frees the data from memory. No PDF files remains outside your device.
For IT security teams: How to verify
You can verify that sakutto never sends your PDF files externally by checking the Network tab in your browser's DevTools while using the tool. You'll see that no requests involving your PDF files are made. This can also serve as documentation for your IT security team.
Questions People Ask
Where does my file actually go?
Nowhere. It is read into the browser tab, compressed there, and written back out to your downloads folder. There is no upload step, so there is no copy of your document on any server of ours to leak or subpoena.
How much smaller will my file get?
Depends entirely on what's inside. Scanned or photo-heavy PDFs usually come down 50–80%. A text-only PDF is already efficient and will only give up 10–30%, so if you were hoping to halve a 40-page text report, expect to be disappointed.
Will the text still be selectable?
Yes, at every level. Compression re-encodes images and strips overhead; it does not flatten your pages into pictures. Search, copy, and text extraction keep working.
How many files can I do at once?
We don't impose a number, but your device's memory does. A few dozen ordinary files is fine. If you're working with very large scans, run them in groups of 10–20 rather than dumping 200 in at once.
Can I compress a password-protected PDF?
Not yet. Remove the password first — our PDF password tool will do it in the browser too — and then compress the unlocked file.
What's the real difference between the three levels?
Low strips metadata and tidies up the file's internal streams, with no visible change to the pages. Standard re-encodes the embedded images, which is where most of the savings come from. High pushes image quality down further; use it when hitting a size limit matters more than how the scans look.
Related Articles
All articlesHow to Upload PDFs to ChatGPT: 4 Methods and Tips for Accuracy
A practical guide to uploading PDFs to ChatGPT based on official information. Covers the four ways to add a PDF, free and paid file limits (512MB per file), tips for summaries and extraction, scanned PDFs, troubleshooting, and handling confidential PDFs.
Business Document Digitization Guide | How to Go Paperless with Free Tools
A complete guide to digitizing business documents and going paperless. Learn how to convert paper to PDF, compress, merge, and split files using free browser-based tools.
File Size Units Explained | KB, MB, GB, TB Conversion Chart
A quick-reference chart for file size units from bytes to terabytes. Includes conversion tables, real-world size examples by file type, email attachment limits, and the Mbps vs MB distinction.
Japanese Tax Return PDF Too Large? How to Compress It for Free
Learn how to compress tax return PDFs for Japan's e-Tax system. Covers the 14 MB file size limit, step-by-step compression instructions, scan settings, and privacy-safe tools.
How to Fill Out & Submit Year-End Tax Adjustment PDFs in Japan
A step-by-step guide to downloading, editing, and submitting nenmatsu-chosei (year-end tax adjustment) PDF forms in Japan. Covers font sizing, password protection, and compression — all with free online tools.
How to Create a Resume PDF | Free, Mobile-Friendly, With Photo
Learn how to create a professional resume PDF for free. Works on your phone, includes photo placement, and covers proper file naming. Your personal information is never uploaded to any server.
Related Tools
PDF Tool List →PDF Merger
Combine several PDFs into one file, in the browser. Drag the pages into the order you want.
PDFPDF Splitter
Pull specific pages out of a PDF, or cut one file into several. Runs locally.
PDFPDF Rotator
Turn sideways or upside-down pages the right way up and save the fix permanently.
PDFPDF Password Tool
Add a password to a PDF, or take one off a file you already have the password for.
PDFPDF to JPG Converter
Turn every page of a PDF into a JPG image, at the resolution you pick. Need PNG instead? There's a separate tool for that.
PDFPDF to WebP Converter
Convert PDF pages to WebP — roughly a third smaller than the same page as a JPG.
PDFPDF to PNG Converter
Convert PDF pages to PNG with no quality loss — the right choice for text, charts, and anything with fine detail.
PDFExtract Images from PDF
Pull the actual photos, charts, and logos out of a PDF at their original resolution — not screenshots of the pages.
PDFWord to PDF Converter
Convert Word (.docx) files to PDF in bulk. Choose whether to merge everything into a single PDF or export one PDF per file.
Browse other tool categories
Find tools by category to match your task.
Popular Reference Charts
Popular reference articles people search for often.