Compress PDF: free online, fast and secure
Scanned PDFs and documents full of photos quickly become 10–50 MB, too large for email and most upload forms. This compressor shrinks PDFs with three levels, so you can choose between perfect text and the smallest file.
Low compression rebuilds the PDF structure without changing any content. Recommended re-saves pages as optimised images at 150 DPI, which works wonders for scans. Extreme goes further for WhatsApp-sized files. The tool always tells you the before and after size.
How to use Compress PDF
- Upload the PDF. Choose the file to compress.
- Pick a level. Low (lossless), Recommended or Extreme.
- Compress and download. See how much smaller it is and download.
Why use ConvertKaro Compress PDF? Free, fast and secure
Here is what makes this Compress PDF tool different from most websites.
100% Free
Every feature of this tool is free for everyone. We do not lock better quality or bigger files behind a paid plan.
Fast results
Your file is processed right inside your browser, so there is no upload or download queue. Most jobs finish in a second or two, even on a slow mobile connection.
Secure and private
Privacy is built in: the conversion runs locally with JavaScript, so your data is never sent to us or anyone else. Close the tab and everything is gone.
No signup, no watermark
No registration and no watermark, ever. What you download is exactly your file.
Works on every device
Works in Chrome, Safari, Edge and Firefox on Android, iPhone, Windows, Mac and Linux. No app to install.
Picks the smaller result
The tool compares lossless and image-based compression and keeps whichever gives the smaller file.
ConvertKaro vs other online converters
| ConvertKaro | Typical online tool | |
|---|---|---|
| Price | Free forever, every feature | Free trial, then paid plans |
| Your files | Stay on your device | Uploaded to a server |
| Signup | Not needed | Often required |
| Watermark or ads on result | Never | Common on free plans |
| Speed | Instant, no upload wait | Depends on upload speed |
| Daily limits | None | Usually limited |
Common uses for Compress PDF
- Emailing documents under the 25 MB limit
- Uploading scans to government and college portals
- Sending PDFs on WhatsApp
- Saving storage on phone and cloud
- Speeding up PDF downloads on websites
Tips for the best results
- Use Low for text documents you need to search or copy from.
- Recommended is best for scanned pages and photos.
- For a hard limit, use Compress PDF to 100KB.
- Removing unneeded pages with Remove PDF Pages also cuts size.
Good to know
There are two kinds of PDFs: digital PDFs created from Word, Excel or a website, which contain selectable text, and scanned PDFs, which are just photos of paper pages. Tools that edit pages, like Compress PDF, work with both. Tools that read text work only with digital PDFs. If you can select a word in your PDF viewer, your file has a text layer.
| Price | Free, no limits |
|---|---|
| Processing | On your device, no upload |
| Signup | Not required |
| Watermark | None |
| Works on | Android, iPhone, Windows, Mac, Linux |
| Category | PDF tools |
How Compress PDF keeps your PDF documents private
When you add a file to Compress PDF, it is opened with your browser’s own engine, processed in memory and offered back to you as a download. ConvertKaro never receives a copy. This is why the tool is fast even on 4G, why there is no daily limit, and why it is safe for confidential PDF documents like ID proofs, bank documents, contracts and family photos.
Using Compress PDF on your phone
On a phone, open this page in Chrome or Safari, tap the main button and pick files from your gallery, Files app or Google Drive. Results download straight to your phone, usually into the Downloads folder or Files app. You can also add this page to your home screen for one-tap access next time.
Who uses Compress PDF?
Compress PDF is used every day by people from many backgrounds, for example:
- Students submitting assignments, certificates and mark sheets
- Job seekers sending resumes and documents
- Accountants and office teams handling invoices and statements
- Small businesses preparing quotations, bills and catalogues
- Anyone filling government, bank or insurance forms online
Supported input: PDF files of any size and page count, including scanned PDFs.
Frequently asked questions
How much can a PDF be compressed?
Scanned and photo-heavy PDFs often shrink by 50–90%. Text-only PDFs are already small and shrink less.
Will text still be selectable?
With Low compression, yes. Recommended and Extreme turn pages into images, so text is no longer selectable.
Why did my PDF not get smaller?
It is already well optimised. Try a stronger level or remove pages.
Is Compress PDF really free?
Yes, completely free. You can use it as many times as you want, and every option on the page is included at no cost.
Is it safe to use Compress PDF online?
Yes. Your files are processed inside your own browser and are never uploaded to our servers, so nobody else can see them.
Does Compress PDF work on mobile?
Yes, the tool is built mobile-first. Open this page on your phone, add your files and download the result directly.
Is there a file size limit in Compress PDF?
There is no fixed limit set by us because files are not uploaded. Very large files depend on your device’s memory; most phones handle files of 100 MB or more without problems.
Will ConvertKaro add a watermark or ask me to sign up?
No. There is no watermark, no login and no email required. Your downloaded file is exactly your result.
Does Compress PDF work offline?
Once this page has finished loading, the tool keeps working even if your internet connection drops, because all processing happens on your device.
Related free tools
You may also find these tools useful: Compress PDF to 100KB, Compress Image, Merge PDF, Remove PDF Pages, PDF to JPG.