Compress PDF Online — 100% Private, No Uploads
Stop uploading sensitive documents to cloud servers. Shrink your PDFs instantly in your browser with our WebAssembly compression engine.
Select a PDF File for Local Processing
Files are processed entirely in your browser — nothing is uploaded to our servers.
Drag & drop a PDF here, or click to browse
Single .pdf file · All sizes welcome
Capabilities & Limitations
Best results on:
- Image-heavy PDFs (scans, brochures, reports with photos)
- Standard JPEG-embedded images
Little to no savings on:
- Text- or vector-only PDFs
- Images using JBIG2, JPEG 2000, CCITT, or Flate encoding (skipped for safety)
Cannot open:
- PDFs with a User Password (AES-encrypted content) — the file will fail to load
Side effects to be aware of:
- Print/edit restrictions (Owner Password) are removed during re-save
- Document metadata (Author, Title, Producer) is stripped
- Loses web-optimised byte ordering and PDF/A compliance
What is PDF compression?
PDF compression is the process of reducing the file size of a PDF without losing the document's readability. The most common technique is image re-encoding: scanned pages, embedded photos, and inline graphics inside a PDF are decompressed, downscaled, and re-encoded with a more efficient JPEG / JBIG2 setting, then put back into the PDF wrapper. Optional steps include stripping embedded fonts, removing document metadata, and converting colour images to greyscale where colour is not required.
SimpleTool's PDF compressor runs entirely in your browser using a WebAssembly build of the open-source MuPDF/Ghostscript pipeline. The source PDF never leaves your device — no upload, no account. Three presets balance quality vs size: Email (target Gmail / Outlook 25MB cap), Standard (general purpose), HD (preserve image fidelity).
Zero-Server Processing
Your documents never leave your computer. We use your browser's internal power to optimize your files.
Smart Quality Presets
Choose from Email, Standard, or HD settings to get the perfect balance between file size and visual clarity.
Lightning Fast
Powered by multi-threaded WebAssembly, our compressor handles large files faster than traditional cloud upload tools.
When do you need to compress a PDF?
Real situations where shrinking a PDF locally beats uploading it to a generic cloud compressor.
Email attachment 25MB limit
Gmail and Outlook cap attachments at 25MB. A 60MB scan of an investor deck, signed contract, or property report needs compression first. The Email preset targets ~20MB output by default — high enough quality to read on screen, low enough to send without splitting.
Government form size limits
Tax filings, visa applications, and patent submissions often impose strict 5-10MB caps per upload. Compressing a scanned-page passport, ID, or supporting evidence PDF inside the browser hits the cap without exposing the document to a third-party processor.
Scanned bank statements
Bank-issued PDFs of paper statements are often massive (10-100MB) because of high-resolution scan quality. For sharing with accountants, landlords, or visa officers, the Standard preset reduces size 60-80% while keeping every digit readable.
Confidential legal documents
Draft settlements, discovery production, and internal memos are exactly the kind of files that should never be uploaded to a generic "compress PDF online" cloud. Local compression in the browser keeps the document on your device while still reducing size for sharing.
Medical records & lab reports
PHI-bearing PDFs from hospitals and labs are typically over 20MB when they include imaging or annotated scans. HIPAA strongly favours not uploading PHI to non-BAA cloud services — local compression sidesteps the question entirely.
WhatsApp / Messenger 100MB cap
Sharing a long-form PDF report or annotated photo book over WhatsApp, Messenger, or Telegram. The 100MB cap is generous but routinely hit by HD-scanned documents. Standard preset usually gets there in one pass.
Storing PDFs on a phone
Mobile devices fill up fast when reference PDFs (textbooks, manuals, archived statements) are stored at full resolution. Bulk-compressing with the Standard preset reclaims 60-80% of the storage without losing the reading experience.
Faster sync to a SaaS DMS
Document management systems (Box, Dropbox, SharePoint) charge by storage and slow down when syncing large PDFs. Compressing PDFs locally before upload reduces both your storage bill and your sync time, especially on slow office WiFi or VPN connections.
How SimpleTool Compares
What each option does, what it costs, and what happens to your file along the way.
| Feature | SimpleTool | Desktop Software | Online Service A | Online Service B |
|---|---|---|---|---|
| Cost | Free | Subscription | Free 1×/day; paid above | Free 1×/day; paid above |
| Files stay private (no upload) | Yes | Yes (desktop app) | No — uploaded to cloud | No — uploaded to cloud |
| Email-target preset (~25MB) | Yes | Yes | Yes | Yes |
| Greyscale option (extra 40% reduction) | Yes | Yes | Paid only | Paid only |
| Removes document metadata | Yes (presets) | Manual | Variable | Variable |
| Bulk compress multiple PDFs | Yes | Yes | Paid only | Paid only |
| File size limit | Browser RAM only | Disk only | Capped on free | Capped on free |
| Works after first page load (offline) | Yes | Yes (desktop) | No | No |
| Account required | No | Yes | No for first compress | No for first compress |
| Source code / data policy | Client-side, no logs | Vendor policy applies | Files retained then deleted | Files retained then deleted |
Comparison reflects publicly documented features as of mid-2026. Vendor terms change — verify on each provider's site before relying on a specific limit.
Why local PDF compression matters
Protecting sensitive data
When you use a generic PDF compressor online, you hand over a decrypted, high-resolution copy of your document to a third-party server. For financial statements, medical records, or legal contracts, this is an unacceptable risk.
SimpleTool solves this by moving the entire optimization logic to your browser's memory.
Metadata removal for cleaner files
Most people don't realise that PDFs carry hidden “footprints” — the name of the author, the exact date of creation, even the software used to make it. Our Standard and Email presets automatically strip this metadata, giving you a clean, anonymous file for professional sharing.
How to compress a PDF efficiently
- Drop your PDF into the tool above.
- Select the Email Friendly preset if you need to bypass the Gmail or Outlook 25MB cap.
- Toggle Greyscale Mode if you're compressing a scanned document — it can reduce size by an additional 40%.
- Download your optimised file instantly.
More Productivity Tools
Explore our other privacy-focused tools designed to boost your productivity
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PDF Merger
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