Check it yourself in two minutes
- Open any file tool, such as Compress PDF, on a desktop browser.
- Press
F12(orCmd+Option+Ion a Mac) and open the Network tab. - Click the small clear icon so the list is empty.
- Select a file and run the tool.
- Look through the new requests. You may see ad or analytics requests, or the page loading its own code, but none of them will carry your file. Sort by size or filter by "Fetch/XHR" to see for yourself.
For an even simpler test, load the tool page, turn off your Wi-Fi, then use the tool. It still works, because all of the processing is local.
What happens to your file
When you pick a file, your browser gives the page permission to read it. The page's code reads the bytes into your device's memory, changes them, and builds a new file. That new file is handed back to you as a download. When you close the tab, the memory is released.
There is one small exception to "in memory". When you use Keep going to send a result to another tool, the file is held in your browser's private storage (IndexedDB) for the moment it takes the next page to load, then deleted. It is never sent to us.
What does the work
| Job | Technology |
|---|---|
| Merging, splitting and editing PDFs | pdf-lib, an open-source library that reads and rewrites the PDF file structure |
| Showing PDF pages and extracting their text | PDF.js, the same engine Firefox uses to display PDFs |
| Converting and compressing images | Your browser's built-in Canvas image encoders |
| Word, Excel and PowerPoint files | JSZip plus our own readers. These formats are ZIP archives of XML files. |
| Hashes and random values | Your browser's Web Crypto API, which is the same one used for secure websites |
| Text, data and format conversion | Plain JavaScript, tested with an automated suite |
The tools that do use a server
The SEO tools check public web pages, and a browser is not allowed to read most other websites directly. So when you enter a URL, our server fetches that one public page and returns it for analysis. The results are not stored. The server refuses private network addresses, limits how much it downloads, and limits how often it can be called.
The contact form also sends what you type to us, as you would expect. Everything else stays on your device.
What local processing cannot do
Being honest about the trade-offs is part of the point:
- Very large files depend on your device. A server farm has more memory than a phone. Tools warn you when a file looks too big for your device.
- Conversions that need heavy software are limited. For example, DOCX to PDF here keeps your text and basic formatting, but cannot reproduce complex page layouts the way Microsoft Word can.
- Some encrypted PDFs cannot be opened. Unlocking works for the older RC4 protection, not for AES.
Each tool page lists its own limits under "Good to know".
What we do collect
Like most websites, we use analytics to see which pages are used, and advertising to pay for the site. Those services use cookies, and visitors in regions that require consent are asked first. They record things like the pages you visit. They do not receive your files or the text you type into tools. The full details are in the privacy policy.