Server-based tools vs browser-based tools
Many online PDF services work like a post office: you upload your file to their servers, their software processes it there, and you download the result. That can work well, but your document spends time on computers you don't control.
A browser-based tool reverses this. The software travels to you instead. When you open a tool page, your browser downloads the page and the program code that performs the task. When you then choose a file, that code runs on your own device and reads the file directly from your disk. The result is created in your browser's memory and saved through your normal download.
What actually happens, step by step
- You open a tool page. Your browser loads the page and its scripts: our own tool code plus well-known open-source PDF libraries (such as pdf-lib and PDF.js) served from a public content-delivery network. This is the same kind of request any website makes.
- You choose a file. The browser gives the page read access to that one file. Choosing a file does not send it anywhere by itself.
- The tool processes it locally. The JavaScript reads the bytes, rearranges pages, renders images or re-saves the PDF — all in memory on your device.
- You download the result. The new file is handed to your browser's download system. It never needed to leave your device.
Because the libraries are already loaded, most tools keep working if your connection drops after the page has finished loading. The two tools that draw pages as images — PDF to JPG and the Extra mode of Compress PDF — fetch one additional helper script the first time they process a file, so stay online until that first run has started.
Why device power matters
With server tools, a data centre does the heavy lifting. Here, your device does. In practice:
- Memory is the main limit. The file, the working copy and the result all live in memory at once. Tools refuse individual files over 150 MB, and phones may struggle well before that with large scans.
- Rendering takes time. Tools that draw pages — PDF to JPG, and Extra compression — handle one page at a time. Long documents take longer on slower devices.
- Keep the tab in front. Mobile browsers may pause or reload background tabs to save battery, interrupting a long job.
What local processing does and doesn't protect
It does mean the file's contents are not transmitted to IQ PDF Manager's server as part of using the tools, so we can't see, store or share them. Your file isn't sitting in someone else's upload folder waiting to be deleted.
It doesn't mean that nothing about your visit is recorded. Like other websites, our hosting provider may log technical information such as your IP address and the pages you visit, and advertising or analytics providers may use cookies — all described in our Privacy Policy. And it can't protect a file on a device that is itself compromised, or a download saved to a shared folder.
In short: local processing removes one significant risk — uploading the document — without claiming to remove every risk. For more, see handling sensitive documents.
How you can check for yourself
Technically minded users can open their browser's developer tools, switch to the Network tab, and run a tool. You'll see the page and script files load when the page opens, but no request carrying your PDF when you process it. You can also load a tool such as Merge PDF, disconnect from the internet, and run it: it still works, because it doesn't need a server to process the file.
Questions and answers
Processing itself doesn't need a server, so once a tool page has loaded, most tools work without a connection. PDF to JPG and Extra compression load one extra helper script on first use, so start them while online. You need a connection to load any page in the first place.
Your own device does the work. On a powerful computer it's often faster than uploading; on an older phone, large files can take longer.