Compress PDF Online

Reduce PDF file size while maintaining quality. Choose your compression level and download the smaller file instantly.

Drag and drop your PDF here

Max file size 100MB. Free, no registration required.

How to Use

1

Upload your PDF file by clicking the upload area or drag and drop

2

Select your preferred compression level: low, medium, or high

3

Click 'Compress PDF' to start the compression process

4

Review the size reduction and download your compressed PDF

Why choose our converter?

Quality, speed, and security for all your conversions.

High-quality conversion

Precise file conversion without any loss of quality.

100% browser-based

Files never leave your device. All processing happens locally.

Works on all devices

Computer, tablet, or smartphone — any browser works.

Fast processing

Convert files in seconds with our optimized engine.

No registration

Start converting immediately. No sign-up needed.

Batch conversion

Convert multiple files at once to save time.

About This Tool

This free online PDF compressor shrinks bloated PDF files so they fit under email attachment caps, upload limits, and storage quotas — without sending your document to a server. Drop in a PDF, pick a compression level, and download a smaller version in seconds. Every byte of the compression happens right here in your browser: no upload, no account, no queue, no watermark.

When You Actually Need to Compress a PDF

Most PDFs that feel "too big" got that way from embedded high-resolution images, scanned pages saved at 300+ DPI, redundant fonts, or inefficient authoring tools (looking at you, Word's default PDF export). You need a smaller file any time a platform rejects it or it chokes a slow connection. Common triggers:

  • Email attachments — Gmail caps at 25 MB, Outlook at 20 MB, and many corporate inboxes reject anything over 10 MB. A quick compress usually gets under the limit.
  • Job application portals — Workday, Greenhouse, Lever, LinkedIn Easy Apply almost all cap resumes and portfolios at 2–5 MB. Scanned work samples blow through this instantly.
  • Government and legal e-filing — Court e-filing systems (PACER, state portals), tax submissions, immigration paperwork routinely enforce 5 MB or 10 MB ceilings per document.
  • Web uploads — CMS platforms, client portals, Dropbox/Google Drive free tiers all benefit from smaller PDFs.
  • Mobile sharing — WhatsApp, Signal, and Telegram trim or refuse big files; compressed PDFs share cleanly.
  • Storage and backup — A folder of compressed PDFs is 50–70% smaller than the originals, meaningful when you archive years of records.
  • Print-on-demand uploads — Lulu, IngramSpark, Amazon KDP have per-file limits you don't want to discover after writing 400 pages.

Low vs Medium vs High — Which Level to Pick

All three levels run on the same core engine but trade quality for size reduction differently:

  • Low compression — Preserves vector text, vector graphics, and original image quality. Optimizes object streams and removes duplicate resources. Size drop: usually 10–30%. Pick this for contracts, resumes, technical diagrams, or anything you'll print or zoom into.
  • Medium compression — Re-renders pages at 150 DPI as JPEGs. Text remains crisp at normal viewing zoom, fine detail in photos softens slightly. Size drop: usually 40–60%. The sensible default for email, uploads, and everyday sharing.
  • High compression — Re-renders pages at 100 DPI. Maximum size reduction, minor softening on text at 200%+ zoom. Size drop: usually 60–80%. Pick this when the upload limit is aggressive and the reader will only skim on-screen.

Rule of thumb: start with medium, check the result, drop to high if you still need smaller, bump to low if text looks fuzzy.

How the Compression Works Under the Hood

On low, we use pdf-lib to parse the PDF, deduplicate repeated images and fonts, strip unused metadata, and rewrite object streams with deflate compression. Nothing is re-rendered — the file structure just gets tighter. On medium and high, we additionally rasterize each page with PDF.js at the target DPI, re-encode the result as a JPEG at a tuned quality factor, and rebuild the PDF around those JPEGs. All of this runs in your browser via WebAssembly; no network round-trip.

When Compression Won't Help Much

  • Already-compressed PDFs — If the file came out of another compressor, squeezing it again gives you 5% at best.
  • Plain text PDFs — A 20-page contract is probably already 200 KB; there isn't much left to remove.
  • PDFs with embedded video or 3D — Our tool focuses on images and text; exotic embedded media is left alone.
  • Digitally signed PDFs — Re-rendering invalidates the signature. If the signature must stay valid, use low compression only, and test that the signature still verifies after.

Compress PDF vs Split PDF vs Print-to-PDF

If your problem is "too many pages" rather than "too big per page," splitting the PDF into parts is often better than compressing — each recipient gets only what they need, and each part fits the limit easily. If you opened the PDF in a viewer and exported via "Print to PDF" as a workaround, you likely got a worse result than this tool — Print-to-PDF has no knowledge of what's safe to discard. And if you need the file to stay under a specific byte count (e.g., exactly 5 MB for a portal), compress, check, and move up or down a level rather than guessing once.

Privacy: Why Browser-Side Compression Matters

The most common reason people compress PDFs — sending financial statements, medical records, signed contracts, tax returns, resumes with home addresses — is also the reason server-side compressors are risky. Many free online tools upload your document to a server, compress there, and may cache it for hours or days. Some explicitly reserve the right to use your files for "service improvement." This compressor never uploads. Your PDF is loaded into your browser's memory, compressed locally, and the result is handed straight back to your Downloads folder. Close the tab and nothing remains on our end.

Frequently Asked Questions

How does PDF compression actually work?
Low compression optimizes the PDF's internal structure — deduplicating fonts and images, tightening object streams, stripping unused metadata — without touching visual quality. Medium and high compression additionally re-render each page as a JPEG at 150 DPI or 100 DPI respectively, which is where the big size savings come from.
Will compressing a PDF reduce its quality?
Low preserves the original quality — it only tightens the file structure. Medium is visually indistinguishable from the original at normal reading zoom; heavy photo detail softens slightly. High is fine for on-screen reading but text edges may look a little fuzzy if you zoom past 200%. Start with medium and step up to high only if you need the extra size drop.
How much smaller can I expect the file to be?
It depends on what's inside the PDF. Image-heavy documents (scanned contracts, photo reports, catalogs) typically shrink 50–80% on medium or high. Text-heavy documents (clean contracts, e-books, exported Word files) shrink 20–40%. Already-compressed PDFs may drop only 5–10% — there's nothing left to squeeze.
What's the largest PDF I can compress?
Up to 100 MB per file. Since compression runs in your browser, very large files are limited by how much memory your browser can allocate — typically comfortable up to 200–300 pages of mixed text and images on a modern laptop.
Can I compress a PDF on my phone?
Yes. The compressor runs in mobile Safari, Chrome on Android, and any modern mobile browser. Large files (50 MB+) may be slower or hit memory limits on older phones; for those, compress on a laptop.
Will compression break a digitally signed PDF?
Medium and high compression re-render the pages, which invalidates digital signatures. Low compression generally preserves signatures because it only touches the file structure, not the content — but always verify the signature still validates after compressing, since some signing providers check the entire file hash.
Does the compressed PDF stay searchable?
On low, yes — text remains as real text you can search and copy. On medium and high, pages become images, so text becomes part of the rendered picture and is no longer selectable. If you need searchable compressed output, stick with low, or run an OCR tool after compressing on medium/high to rebuild a text layer.
Why is my compressed PDF actually bigger than the original?
This is rare but possible when the original was already highly optimized or mostly vector content, and you picked a high compression level that rasterized everything at 100 DPI — the JPEG overhead can exceed the original vector data. Use low compression for these files, or leave them alone.
Is there a limit on how many PDFs I can compress per day?
No. No daily cap, no sign-up, no email capture, no paywall. Compress as many files as you want, as often as you want. The tool stays free because compression happens on your device, not on our servers.
Is my PDF uploaded anywhere during compression?
No. The entire compression runs in your browser via WebAssembly. Your file is loaded into browser memory, processed locally, and the result is saved to your device. It's never sent to our servers, never logged, and never cached remotely. Close the tab and the file is gone from our side — because it was never there.

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