Compress PDF
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When you'd need to compress a PDF

The usual reason is that something is rejecting your file because it's too big. Gmail caps attachments at 25 MB, Outlook at 20 MB, and most corporate mail servers at 10 MB or less — the limits weren't set with you in mind. Government portals are often stricter: the IRS expects e-filed forms in tight size envelopes, USPTO patent filings have per-document caps, PACER court e-filing has per-document and per-filing limits, HMRC and Companies House submissions cap per upload, and most state and city government e-services do the same. E-signature platforms (DocuSign, Adobe Sign, HelloSign), applicant tracking systems (Greenhouse, Lever, Workday), and procurement portals (SAP Ariba, Coupa) all have their own ceilings. If your PDF won't go through, compressing it is usually the fastest path.

The other reason is sharing. A 50 MB contract sent over WhatsApp or Slack works, but downloads slowly on the other side. A scan of three receipts that comes off the phone at 80 MB is awkward to attach to an expense report in Concur or Expensify. Smaller files are just easier to move around.

Pick a quality, see what comes out

The tool has two modes. In quality mode, three tiers — high (close to the original), medium (the balanced default that works for most files), low (noticeably smaller at the cost of sharpness). In size mode, you pick a concrete number — 50 KB, 100 KB, 200 KB, 500 KB, or 1 MB. The tool starts at high quality and steps the quality down until the result fits the size you asked for. There's no wrong choice; the right one is the smallest file that still looks acceptable to you. Most people land in the middle.

Two things to know about how this tool compresses. First, it works by re-rendering each page into a JPEG and assembling the new PDF as a sequence of those images. That's how it gets predictable, large size reductions on photo-heavy or scanned content. Second — the trade-off worth knowing — the result is a PDF made of pictures. You won't be able to select or copy text from the compressed file. If you need the text to remain searchable or selectable (for indexing, for plagiarism checks, for archive systems that search content), this isn't the right tool for that PDF.

One honest detail: sometimes the tool returns the original unchanged. For some files (small text PDFs without images), rasterizing the pages would produce a larger file than the input — and there's no point handing you a bloated version. The tool checks and falls back to the original when that happens. Pre-baked shortcuts for common targets: 100 KB, 200 KB, 1 MB.

What kinds of PDFs compress a lot, and which ones don't

Scanned documents — contracts you photographed, receipts, hand-written notes, anything that started as an image of paper — compress dramatically. A 50 MB scan often comes out at 5 MB or smaller without visible quality loss for normal reading.

Clean digital PDFs — invoices generated by software, reports exported from Word or Excel, anything made directly on a computer — usually have less to give back. They're already small to begin with, and the way this tool works (re-rendering pages as images) can occasionally make a clean PDF slightly larger instead of smaller. If you started with a 2 MB Word export, don't expect to get to 200 KB.

Mixed PDFs (text plus a few embedded photos) sit in the middle. The photo content shrinks; the text rasterises into the new file size.

Practical tips

1. Compress is the last thing you do, not the first. If you need to fix a typo, sign the document, or merge it with something else, do that first. Once the PDF is compressed (and the text becomes part of the image), editing it later is much harder.
2. If your PDF has a password, unlock it first. Run it through unlock-pdf before compressing.
3. Open the compressed file before sending. Look at the first page — is the text still sharp enough to read? Are the photos clear? If not, step the slider up and re-run. The result is yours to judge before sending.
4. For very large PDFs (hundreds of MB), split first. Compression runs in your browser; very large files can run out of memory, especially on a phone. Split with split-pdf, compress each part, then re-combine with merge-pdf.

When compressing here isn't the right move

• If your document needs to stay searchable. Legal filings indexed by case-management software, academic submissions checked for plagiarism, archive copies that need to be searchable later — they all rely on selectable text. Don't compress those here. Send the original or use a different compressor.
• If your document is signed digitally. A digital signature is tied to the exact file. Compressing changes the file, which breaks the signature. Don't compress signed documents.
• If your document needs to be PDF/A. Some archives and government workflows require a specific archival format. Compression here doesn't preserve that.
• If it's a technical drawing or schematic. Engineering drawings, CAD exports, and detailed diagrams have crisp lines that look bad when re-rendered as images. The result will be both larger than the original and worse-looking. Send the original.

Everything else — receipts, scans, mixed-content PDFs, photo-heavy files — compresses cleanly here, runs entirely in your browser, and never leaves your device.