Compress PDF online — structural rewrite, free and in your browser

Drop your file, pick Medium or Strong, and check the before/after size the tool shows you. Honest expectation-setting: this compressor rewrites the file structure and strips metadata, it does not touch images — so if your PDF is over 25 MB because it is full of scans, it will probably still be over 25 MB afterwards. What actually works in that case: split the document into two or three parts with our splitter and send two emails, or run it through the AI in the documents workspace, which does re-encode images. Gmail (consumer and Workspace) caps at 25 MB, Outlook.com / Microsoft 365 and iCloud Mail at 20 MB. Text-heavy documents — legal briefs, reports, exports from older tools — are where the structural rewrite genuinely pays off.

You cannot hit a specific byte target with this tool, and we would rather say so than let you upload a file and find out. There is no target-size mode and no image downsampling: you pick a level, the file is rewritten, and you see what you get. If a portal demands 500 KB and your document is a colour scan, the physics are unforgiving — reaching that size means grayscale at 72 DPI with heavy JPEG loss, and the text goes blurry. The realistic routes are: convert the pages to JPG at 72 or 150 DPI and rebuild the PDF, split the document, or use a compressor that re-encodes images. Smallpdf ($9/mo Pro), Pi7, Zamzar and PDFgear all advertise “compress to 1 MB” and make exactly that quality trade-off behind a vague slider.

Yes. No signup, no credit card, no 2-documents-per-day cap (the Smallpdf free-tier limit), no 3-tasks-per-hour cap (Sejda free), no Adobe ID required after 2 compressions (Adobe Acrobat online). Compress hundreds of files in a row if you need to. The whole tool runs in your browser via WebAssembly, so we have no server cost to ration. Adobe Acrobat Pro is $19.99/mo, Smallpdf Pro $9/mo, iLovePDF Premium $7/mo, Sejda Premium $7.50/mo, Foxit $9.99/mo, Soda PDF $7.99/mo, CloudConvert $9.99/mo, ILoveImg $4/mo.

Your PDF stays in your browser: iFillPDF compresses entirely client-side using WebAssembly + pdf-lib under ISO 32000-2:2020. Your file never leaves your device — not to us, not to AWS US-East-1, not to anyone. Competitors (iLovePDF, Smallpdf, PDF24, Adobe Acrobat online, Sejda, Foxit, Soda PDF, CloudConvert) all upload to their servers. Even when the page has loaded you can disconnect the network cable and keep compressing — the WebAssembly engine runs offline.

Text and hyperlinks: yes, untouched, Ctrl+F still finds your terms. Images: untouched too, at full original resolution, because this compressor never opens them. Form fields: yes on Light and Medium, no on Strong — Strong deliberately flattens interactive fields into static page content, which is what makes it the smallest option and also what makes the form no longer fillable. Document metadata: cleared on Medium and Strong by design. Digital signatures: invalidated, because re-saving a PDF rewrites the byte ranges the signature covered. If your file is signed and must stay signed, do not compress it.

It depends entirely on what is making your file big, and the answer is often “not much” — which is why the tool shows you the before and after size instead of promising a percentage. Files whose weight is structure (documents exported by older tools, PDFs assembled from many sources, forms with heavy metadata) can lose a real slice. Files whose weight is images — scanned contracts, photo portfolios, PowerPoint exports — barely move, because the images are copied across untouched. Foxit, Smallpdf and Adobe Acrobat advertise “up to 99%” compression; that number comes from re-encoding images at low quality on uncompressed scans straight out of a Xerox or Brother MFP, and it is not what this tool does.

It is GDPR-by-design, not just compliant. Because no personal data ever leaves your device (the compressor runs in your browser via WebAssembly), there is no data transfer to log under GDPR Art. 30, no processor agreement to sign under GDPR Art. 28, no Transfer Impact Assessment to file under GDPR Art. 46. Static assets and any optional account data sit in Frankfurt eu-central-1 (Hetzner Falkenstein, ISO 27001-aligned, TADPF) — outside the reach of the US Cloud Act and 50 USC §3024. HIPAA BAA available with the Lifetime offer for orgs that want a paper trail. Even EU-hosted competitors still process your file on their infrastructure; iFillPDF keeps the split in your browser tab. Material risk reduction for FRCP Rule 34 ESI productions, attorney-client privileged material, HIPAA PHI and trade secrets.

100 MB — the drop zone rejects anything larger, and below that your browser memory is the practical ceiling since everything runs in the tab. Smallpdf caps free users at 5 MB (Pro $9/mo to lift), iLovePDF at 25 MB (Premium $7/mo), Sejda at 50 MB and 200 pages free, Adobe Acrobat online at 100 MB, PDF24 at 100 MB — the same ceiling as ours, without the upload.

Yes — once the iFillPDF page has loaded, you can disconnect from the internet and keep compressing. The WebAssembly engine runs entirely in your browser tab. Try that with iLovePDF, Smallpdf, PDF24, Adobe Acrobat online, Sejda, Foxit, Soda PDF or CloudConvert — all of them require a live connection to upload your file to their server.