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Compress PDF

Reduce PDF file size without losing quality

This workflow reads the selected file from browser memory and creates the download locally. AntiUpload, analytics, and ads receive neither the file nor its working buffers.

  • No file upload
  • Runs on your device
  • Ads cannot access files
  • No account

Drop your PDF file here

or

Up to 200MB on this device — processed in RAM, never uploaded

100% Local Processing
Zero Server Uploads

About Compress PDF

Compress PDF keeps the complete file workflow inside this browser tab. Your selected file, its name, contents, settings, and generated output are not sent to AntiUpload or a cloud conversion service. Ads and aggregate traffic analytics stay outside the processing boundary and receive no file object or working buffer.

Compress PDF reduces the file size of a PDF document so you can email it, upload it to systems with attachment limits, or save storage space. AntiUpload's PDF Compressor optimizes embedded images, removes duplicate streams, and flattens unnecessary object overhead — without visually changing the document for typical reading use. Three compression levels let you trade quality for size: Low for minimal visible change (good for text documents), Medium for balanced results (the default), and High for maximum reduction (images become slightly softer but remain readable).

Compression runs entirely in your browser, so the source PDF is not sent to a cloud conversion service. There is no server queue or per-day processing quota; the practical ceiling comes from the memory and speed of your device. That local model is especially useful for contracts, records, and other files that should not be copied to a third-party processor.

The tool is built on a hand-tuned PDF re-serializer (pdf-lib + custom image transcoding via @jsquash/jpeg and @jsquash/oxipng). Typical scanned PDFs shrink 50–80% at Medium. Text-only PDFs (digital exports from Word / LaTeX) shrink less, around 10–30%, because they're already efficient. PDFs with heavy embedded graphics — brochures, manuals, slide decks exported from Keynote / PowerPoint — see the biggest wins. The compressed output remains a valid PDF, opens cleanly in Acrobat / Preview / Chrome / mobile readers, and preserves text searchability and selectability.

How it works

  1. Drop the PDF you want to shrinkUpload your file — its current size is displayed so you can compare to the output. no upload caps from us; the constraint is your device's RAM (up to ~1.5 GB on desktop, less on mobile).
  2. Pick a compression levelLow preserves maximum quality; High gives the smallest file. Medium is the default and works for 90% of documents. Switch between them and re-compress to compare outputs — the source file stays on your device, so there's no upload cost to iterating.
  3. Click CompressThe tool re-optimizes images, removes redundancy, and rewrites the PDF — all locally. Typical files shrink 30–70% depending on image content. Progress bar shows real-time per-page progress.
  4. Download or compress another fileResult downloads instantly (no upload-back round trip). Click 'Process another file' to loop back to the picker — useful for batch-compressing a folder of attachments before emailing.

When to use Compress PDF

Emailing attachments that exceed provider limits
Gmail caps attachments at 25 MB; Outlook and corporate systems vary by tenant. Use target-size mode for a specific portal limit, then verify the generated size before attaching it.
Uploading to forms with size restrictions
Visa applications, online tax portals, university applications, and job application portals often limit PDFs to 2–5 MB total. Compress to fit — High preset usually gets text-heavy PDFs under 2 MB.
Archiving PDFs with limited cloud storage
When your Dropbox or Google Drive is full, compressing large PDFs can reclaim significant space. A folder of compressed PDFs typically takes 30-50% less space than the originals.
Speeding up sharing links
A 2 MB PDF loads in seconds; a 30 MB PDF makes recipients wait. Compress before sharing for a better recipient experience — particularly important when sharing with mobile users on metered connections.
Reducing law-firm / accounting brief sizes
Court e-filing systems frequently cap submissions at 25 MB per document. Multi-exhibit briefs blow through this. Compress to fit without breaking exhibits into parts — and without uploading privileged client content to a third-party cloud service.
Compressing scanned receipts / invoices for expense reports
Expense systems like Concur and Expensify reject attachments over 5 MB. Phone-scanned receipts often hit 15-20 MB. High compression brings them under cap while keeping text readable.

Frequently asked questions

Is my PDF really not uploaded anywhere?
Confirmed. Open DevTools → Network → reproduce a compression. No request contains your PDF. The only network traffic is the page JavaScript and (on first use) the pdf-lib / @jsquash compression libraries. After first load you can disconnect from the internet and compression still works — proof that nothing is uploaded. Input files are read from browser memory and the output is created locally for your download. AntiUpload does not send file bytes, names, sizes, page counts, contents, passwords, or generated outputs through analytics or advertising requests.
How to compress a 50MB PDF to under 10MB for free?
Choose Target size and enter 10 MB. The compressor walks a text-preserving image-quality ladder toward the budget and reports when the document cannot safely reach it without flattening. If necessary, explicitly allow exact-size flattening or split the PDF into smaller parts.
How much will my file shrink?
It depends on content. Text-heavy documents shrink modestly (10–30%); image-heavy PDFs (scanned documents, brochures, slide decks) often shrink 50–80% at Medium. Pure-text PDFs already exported efficiently see the smallest gains; scanned-image PDFs see the biggest. PDFs with embedded fonts that aren't subset see notable savings from font-subsetting alone.
Will compression affect text readability?
No. Text is not compressed lossy — it remains crisp and searchable at every compression level. Only embedded images lose some quality, and only at High compression noticeably. Optical-character-recognition (OCR) text behind scanned pages remains accurate after compression.
Best free no-watermark PDF compressor online?
Choose a compressor that shows its quality tradeoff, verifies the result, and fits your privacy requirements. AntiUpload has no sign-up, watermark, or server queue because compression runs locally, and it offers both quality presets and a measured target-size workflow.
Which level should I pick?
Medium for most documents. Low if the PDF is print-destined or already small. High if you need the smallest possible size and some image softening is acceptable. For text-only documents the levels barely differ — Low produces nearly identical output to High.
Can I compress a compressed PDF further?
Usually not by much — the second pass of compression has diminishing returns. If you need a smaller file, try a higher compression level on the original instead of re-compressing. Re-compressing an already-optimized PDF sometimes saves <5% on size while slightly degrading image quality.
Does the tool work on password-protected PDFs?
No. Remove the password first — open the PDF in any viewer with the password and save an unencrypted copy — then compress that. PDF encryption blocks the image-extraction step compression needs.
Does this PDF compressor work on Windows, Mac, iPhone, and Android?
Yes. It runs entirely in your web browser, so it works on any device with a modern browser - Windows, Mac, Chromebook, iPhone, or Android - with nothing to install.
Is there a maximum PDF file size I can compress?
There's no server-side upload limit because your PDF never leaves your device - it's processed locally in your browser. The practical ceiling is your device's available memory, so very large files compress best on a desktop.
Do I need to sign up or create an account to compress a PDF?
No. There's no sign-up, account, or email required - open the page and compress your PDF right away.

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