Looking for the best free PDF compressor online? With dozens of tools available, choosing the right one can be overwhelming. Some upload your files to servers (privacy risk), others add watermarks, and many have strict limits on free usage.
We tested the most popular PDF compressors to help you find the best option for your needs.
Quick Comparison Table
| Tool | Privacy | Free Limits | Watermarks | Compression |
|---|---|---|---|---|
| Edesy | Files stay local | Unlimited | None | Excellent |
| iLovePDF | Server upload | 1 file/hour | None (free) | Good |
| SmallPDF | Server upload | 2 files/day | None (free) | Good |
| Adobe Acrobat | Server upload | Account required | None | Excellent |
| PDF24 | Server upload | Unlimited | None | Good |
Pricing Comparison
The prices below are the ones stated in the tool reviews later in this article, collected in one place. Vendor pricing changes without notice - verify on the vendor's own page before deciding.
| Tool | Free tier | Paid plan | What the paid tier buys |
|---|---|---|---|
| Edesy | Unlimited, no account | None | n/a - the tool is free |
| iLovePDF | 1 file per hour | From $4/month | Removes the hourly limit, batch processing |
| SmallPDF | 2 tasks per day | $12/month (desktop $108/year) | Removes the daily cap |
| Adobe Acrobat | Very limited | $22.99/month | Full Acrobat feature set, not just compression |
| PDF24 | Unlimited | None | n/a - the tool is free |
Two of the five are free at any volume. The paid tiers are mostly buying you throughput - the removal of a file-per-hour or task-per-day cap - rather than better compression. If you compress a few PDFs a month, the free tiers of any of these will do; if you compress in bulk, the question is whether you would rather pay for a cap to be lifted or use a tool that never had one.
If you need an exact output size rather than "smaller", none of the free tiers above target a number. Use Compress PDF to Size, which iterates on quality until it lands near a target you set (100KB, 200KB, 500KB, 1MB, 2MB or 5MB).
The Privacy Problem with Online PDF Tools
Here's something most people don't realize: when you use most online PDF tools, your files are uploaded to their servers. This means:
- Your confidential documents are stored on third-party servers
- Files may be retained for hours or days
- You're trusting the service with sensitive information
- Some services scan uploaded files for various purposes
This is particularly concerning for:
- Business contracts and legal documents
- Financial statements and tax forms
- Medical records and personal information
- Proprietary business data
The Solution: Use a tool that processes files locally in your browser. Our PDF compressor never uploads your files anywhere - everything happens on your device.
Detailed Tool Reviews
1. Edesy PDF Compressor (Best for Privacy)
Pros:
- 100% client-side processing - files never leave your device
- No file size limits (depends on your device memory)
- No daily usage limits
- No watermarks
- No signup required
- Works offline after page loads
- Three compression levels (Low, Medium, High)
- Shows exact reduction percentage
Cons:
- Requires modern browser (Chrome, Firefox, Safari, Edge)
- Processing speed depends on your device
Best For: Anyone who values privacy, works with confidential documents, or needs unlimited compressions.
If you need an exact size: the three compression levels above optimise for quality, not for a number. When a portal demands "under 200KB", use Compress PDF to Size instead - same client-side processing, but it iterates on quality until it lands near the target you set (100KB, 200KB, 500KB, 1MB, 2MB or 5MB). For the most common form limit there is a one-click version: compress PDF to 200KB, which opens with the 200KB target already set. For stricter 100KB limits there is compress PDF to 100KB.
Compression Test Results:
- 45MB image-heavy PDF → 6.2MB (86% reduction on High)
- 12MB mixed PDF → 4.1MB (66% reduction on Medium)
- 8MB text PDF → 6.8MB (15% reduction on Low)
2. iLovePDF
Pros:
- Easy to use interface
- Good compression quality
- Multiple PDF tools available
Cons:
- Files uploaded to servers (privacy concern)
- Free tier limited to 1 file per hour
- Premium required for batch processing
- $4/month minimum for full features
Best For: Casual users who don't need privacy and only compress occasionally.
3. SmallPDF
Pros:
- Clean, modern interface
- Good compression quality
- 21+ PDF tools available
Cons:
- Files uploaded to servers
- Free tier limited to 2 tasks per day
- $12/month for Pro features
- Desktop app is expensive ($108/year)
Best For: Users willing to pay for a full PDF suite.
4. Adobe Acrobat Online
Pros:
- Industry-standard compression
- Excellent quality preservation
- Part of Adobe ecosystem
Cons:
- Requires Adobe account
- Files processed on Adobe servers
- Free tier is very limited
- Full version costs $22.99/month
Best For: Users already in the Adobe ecosystem.
5. PDF24 Tools
Pros:
- Many free tools
- No account required
- Decent compression
Cons:
- Files uploaded to servers
- Interface is cluttered
- Some features require desktop software
Best For: Users who need various PDF tools and don't mind server uploads.
Compression Quality Comparison
We tested each tool with the same 45MB PDF containing mixed content (text, images, charts):
| Tool | Output Size | Reduction | Quality |
|---|---|---|---|
| Edesy (High) | 6.2 MB | 86% | Good |
| Edesy (Medium) | 9.8 MB | 78% | Very Good |
| iLovePDF | 8.1 MB | 82% | Good |
| SmallPDF | 7.9 MB | 82% | Good |
| Adobe | 6.5 MB | 86% | Excellent |
| PDF24 | 8.4 MB | 81% | Good |
Verdict: Adobe and Edesy offer the best compression ratios. Edesy wins on privacy since files never leave your device.
Security and Privacy Comparison
| Tool | File Processing | Data Retention | Privacy Level |
|---|---|---|---|
| Edesy | Local (browser) | None | Excellent |
| iLovePDF | Server | 2 hours | Poor |
| SmallPDF | Server | 1 hour | Poor |
| Adobe | Server | Varies | Moderate |
| PDF24 | Server | Unknown | Poor |
For sensitive documents, client-side processing is essential. Only Edesy processes files entirely in your browser.
Features Comparison
Compression Options
| Tool | Compression Levels | Custom Settings |
|---|---|---|
| Edesy | 3 levels | No |
| iLovePDF | 3 levels | Yes (paid) |
| SmallPDF | 2 levels | Yes (paid) |
| Adobe | Multiple | Yes (paid) |
| PDF24 | 3 levels | Yes |
Platform Support
| Tool | Web | Windows | Mac | iOS | Android |
|---|---|---|---|---|---|
| Edesy | Yes | Via browser | Via browser | Via browser | Via browser |
| iLovePDF | Yes | Yes | Yes | Yes | Yes |
| SmallPDF | Yes | Yes | Yes | Yes | Yes |
| Adobe | Yes | Yes | Yes | Yes | Yes |
| PDF24 | Yes | Yes | No | No | No |
When to Use Each Tool
Use Edesy When:
- Privacy is important (legal, medical, financial documents)
- You need unlimited compressions
- You want no watermarks or signup
- You're on a budget (it's free!)
- You work offline sometimes
Use iLovePDF/SmallPDF When:
- You only compress PDFs occasionally
- Privacy isn't a major concern
- You want a simple interface
Use Adobe When:
- You're already paying for Adobe Creative Cloud
- You need other Adobe integrations
- Maximum quality is essential
How to Get the Best Compression Results
Regardless of which tool you use, follow these tips:
1. Choose the Right Compression Level
- High compression for email attachments and web uploads
- Medium compression for general sharing
- Low compression when image quality is critical
2. Remove Unnecessary Pages First
Use a PDF page removal tool to delete blank pages, covers, or irrelevant sections before compressing. If the PDF is password-protected, unlock it first: most compressors can't open locked files.
3. Compress Individual Files Before Merging
If combining multiple PDFs, compress each one first, then merge. This often produces better results than compressing a merged file.
4. Consider the Source
PDFs from scanners are often larger than necessary. Use OCR to convert scanned images to text-based PDFs for smaller file sizes.
5. Drop the Colour If You Do Not Need It
A colour scan carries three channels of image data. If the document is text, signatures or a form that will be printed in black anyway, converting it with Grayscale PDF cuts size before you compress - and often means you can use a gentler compression level afterwards.
Our Recommendation
For most users, we recommend Edesy PDF Compressor because:
- Complete Privacy: Your files never leave your device
- No Limits: Compress as many PDFs as you need
- No Cost: Completely free, no hidden charges
- No Watermarks: Clean, professional output
- Works Everywhere: Any modern browser on any device
If you need additional features like digital signatures or PDF editing, consider pairing Edesy with specialized tools rather than paying for an all-in-one suite.
Try It Now
Ready to compress your PDFs? Try our free PDF compressor - no signup required, files never leave your device.
More PDF Tools:
- Compress PDF - Reduce file size
- Merge PDF - Combine multiple PDFs
- Split PDF - Divide PDFs into parts
- PDF to Word - Convert to editable Word
- PDF to Excel - Extract tables to Excel