Why we built it
Most PDF jobs are small and urgent. A form wants your certificate under 200 KB. A loan portal won't take a locked bank statement. A scan came out sideways. The popular PDF sites handle these by uploading your file to their servers, then ask you to wait, sign up, or come back tomorrow when the free limit resets.
The files involved are often the most private ones people have: ID cards, bank statements, salary slips, contracts. We didn't think they should travel to someone else's server just to be made smaller. Phones and laptops are now fast enough to do this work themselves, so on PocketPDFs, they do.
How it works on your device
When you open a tool, the page downloads the code it needs. When you drop a file, your browser reads it from your device, does the work in memory and hands the result back as a download. There's no upload step, which is also why there's no upload wait, and why most tools keep working in airplane mode once the site has loaded.
We build on well-known open-source software:
- pdf-lib, to build and change PDFs;
- PDF.js from Mozilla, the PDF reader inside Firefox, to read pages and draw previews;
- qpdf, compiled to run in the browser, for passwords and for shrinking files without losing anything;
- MozJPEG through jSquash, to re-encode photos and scans when compressing;
- libheif, to open iPhone HEIC photos.
The full list, with licences, is in our terms.
How we test
Every tool has automated tests that use it the way you would. They click Choose or drop a real file onto the page, press the button, and open the download to check it. Are the pages in the right order? Is the file under the size limit? Does the password work? There are more than 450 of these tests. They run in Chrome, and again in a mode that behaves like Safari 17, the version on many older iPhones and Macs.
We also try to break it. Every operation runs against 18 hand-made broken and hostile PDFs: a download cut off halfway, a file that claims a billion pages, pages that point at each other in a loop, a 52 KB photo that unpacks to 50 MB. Each one has to end with a result or a clear message, never a frozen tab.
The compress-to-size pages carry real measurements. We ran each size on five everyday documents (phone photos of a certificate and of a letter, colour scans at 300 and 200 DPI, and a report from Word) and kept every file that came back. The tables on those pages show the results as they came out, including the ones that didn't fit. You can see them onCompress PDF to 200 KB, for example.
The guide under each tool is checked against the tool itself. Button names, examples and numbers come from what the tool really does or from those measurements, and each guide shows the date it was last checked. When a tool changes, its guide is checked again.
What we won't do
- Show ads. Not now, not later.
- Send a file to a server without telling you first. If a future tool needs our server, its page will say so before you start.
- Sell or share your data. We never have your files to begin with.
- Ask for a card to start a free trial, or renew anything by itself.
- Put fake download buttons, countdowns or pop-ups between you and your file.
- Record file names, file contents or anything you type. The privacy policy lists exactly what we count.
Get in touch
Found a bug, a file that won't work, or a guide that's wrong? Write to privacy@pocketpdfs.com. It's our one address for now, so any question is welcome there, not only privacy. Please don't attach private documents: describe the problem, or send a file with nothing personal in it.