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What is the compress pdf?
GigAI Compress PDF re-renders each page and re-encodes it with MozJPEG, entirely in your browser - the document is never uploaded. In our published benchmark a 6.6 MB image-heavy PDF became 90 KB (99% smaller) in 2.2 seconds. If compression can't beat your original, you get the original back. Free, no account, no daily limit.
The GigAI PDF Compressor shrinks bulky PDFs without sending them anywhere. It renders each page and re-encodes it as an optimized JPEG using a quality profile you pick, which is especially effective on scanned documents and image-heavy files where most of the weight lives in pictures. Everything runs in your browser with pdf.js and pdf-lib, so there's no upload, no queue and no watermark. We're upfront about the method: this is a genuine, lossy recompression rather than server-grade structural optimisation, so vector text becomes part of the page image. If a file happens to compress larger than the original, as pure-text PDFs sometimes do, the tool simply hands your original back unchanged. You always see the exact saving before you download.
- Difficulty:
- Easy
- Typical time:
- ~15s
- Processing:
- 100% browser processing
Last updated
How to use the compress pdf
- 1
Upload your PDF
Drag a single PDF onto the drop zone, or click to browse. The tool reads it locally. Nothing is sent anywhere.
- 2
Choose a level
Pick Low, Medium or High. Higher levels reduce quality further for a smaller file. Low keeps pages sharpest.
- 3
Compress
Hit Compress PDF. Each page is rendered and re-encoded on your device, with a progress bar for longer documents.
- 4
Review & download
Check the before/after sizes and percentage saved. Happy with it? Download. Want more savings? Try a higher level.
What Compress PDF includes
Low, Medium & High levels
One control trades quality against savings. Low keeps pages crisp for a modest cut. High is aggressive when you just need the file to fit.
See the exact saving
Original size, compressed size and the percentage reduced are shown side by side, so you know precisely what you gained before downloading.
Best on scans & image PDFs
Compression re-encodes each page as a JPEG, so scanned documents, photo brochures and slide exports typically shrink the most.
100% in your browser
Your PDF is read and recompressed locally with pdf.js and pdf-lib. It's never uploaded, stored or seen by anyone: privacy holds on every page.
Never returns a bigger file
If recompression can't beat the original (common for pure-text PDFs) the tool returns your original bytes untouched rather than inflating it.
Why use our compress pdf
Honest about the method
This is real, lossy JPEG recompression, not magic. We tell you plainly that text is flattened into the page image, so you can choose the right level.
Fits email & upload limits
Bring a report under a 10 MB mail cap or a portal's upload ceiling in seconds, without splitting the file or losing a page.
Free with no watermark
No account, no daily quota, no paywall and nothing stamped on your pages, compress as many PDFs as you like at no cost.
Private by design
Because compression runs on your device, sensitive contracts and scans never leave it. Close the tab and every trace is gone.
Built for the way you work
From quick one-off fixes to daily workflows, see how people put this tool to use.
- Professional
Email a heavy client deck
Squeeze an image-rich proposal or slide export under your mail server's attachment cap so it sends first time, without a file-sharing link.
- Student
Meet a portal upload limit
Trim a scanned thesis or assignment below a submission system's size ceiling so it uploads before the deadline, no pages dropped.
- Business
Slim an archive of scans
Reduce months of scanned invoices and receipts to a fraction of their size for cheaper storage and faster syncing across devices.
Measured results
Numbers from running this exact tool against a fixed public sample, not marketing claims.
| Sample | a 6.6 MB, 2-page image PDF built from the test photograph |
|---|---|
| Result | 6.6 MB → 90 KB (99% smaller) in 2.2 seconds |
| Worth knowing | Pages are re-rendered and re-encoded with MozJPEG. The output is returned unchanged if compression can't beat the original. Text-first PDFs compress far less - they're already small. |
Measured on 2026-08-22 using Chromium on an Apple-silicon MacBook Air, everything in-browser. Re-measured with each release. The harness and samples are part of this site's test suite.
What this tool does not do
Boundaries stated plainly, with the right tool for each neighbouring job.
- It does not split a document into parts. Split PDF does that.
- It does not remove pages - every page stays, smaller. Delete PDF Pages does that.
Supported formats
Accepts PDF, and produces PDF, all processed locally in your browser.
Input formats
Output formats
Frequently asked questions
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Comparisons & guides
Go deeper on the concepts behind the compress pdf.
PDF vs DOCX: Which Document Format Should You Send?
ComparisonPDF is a fixed, look-identical-everywhere format for final documents. DOCX is Word's editable working format. Here's exactly when to use each, and how to convert between them.
Read the comparisonGigAI Tools vs iLovePDF: Which PDF Toolkit Should You Use?
ComparisonBoth give you a complete set of PDF tools. The real difference is architectural: iLovePDF processes your file on its servers, GigAI processes it in your browser. Here's when each one is the right call.
Read the comparisonHow to Compress a PDF (Free, In Your Browser)
GuideShrink a large PDF in seconds. No software, no upload, no watermark. A simple step-by-step guide to reducing PDF file size while keeping it readable.
Read the guideHow to Merge PDF Files Into One (Free, No Upload)
GuideCombine several PDFs into a single document in seconds: reorder pages, no software, no watermark. A step-by-step guide to merging PDF files in your browser.
Read the guideHow to Add a Watermark to a PDF (Text or Image)
GuideStamp DRAFT, CONFIDENTIAL or your logo across every page of a PDF, control the opacity, angle and position. A quick, private, browser-based guide.
Read the guideGuides & articles
- pdf-tools
- pdf-tools
The Complete Guide to PDF Compression
How PDF compression actually works, the difference between lossy and lossless methods, what browser tools can and can't do, and how to choose the right level
4 mins read 
pdf-toolsReduce PDF Size Without Losing Quality
A practical look at where PDF weight really comes from, when compression is worth it, and how to shrink a file while keeping it perfectly readable.
4 mins read
Common problems, solved
Hit a snag? Here are quick fixes for the issues people run into most.
My PDF barely got smaller.
Text-only PDFs are already compact, so there's little to reclaim. This tool shines on scans and images. Try a higher level. If the result would be larger, we return your original unchanged.
The text is no longer selectable after compressing.
That's expected: compression rasterises each page into an image, which flattens live text. If you need selectable text, keep the original or run our OCR PDF tool on the compressed file.
Pages look soft or blurry.
You likely used High compression. Re-upload the original and choose Medium or Low for a gentler quality cut, or accept a slightly larger file for sharper pages.
Get the most out of it
Start on Medium. It balances size and quality well. Only reach for High when a hard limit forces it.
Scanned or photo-heavy PDFs compress far more than text documents, so set expectations by what's inside the file.
Need both small AND selectable text? Compress first, then run OCR PDF to add a searchable text layer back.
Merging several files? Combine them with Merge PDF first, then compress once, it's faster than compressing each separately.
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Your privacy is built in
Your PDF is compressed entirely in your browser with pdf.js and pdf-lib, it's never uploaded to any server. Nothing is stored, logged or shared, so when you close the tab every page is gone.
- Runs in your browser
- No uploads
- Nothing stored
Ready to try the compress pdf?
Free, private and instant. Compress PDF runs right in your browser.