What we want in a PDF web app
This whole journey started with helping my father with financial documents.
He sent me photos (HEIC files) that needed to become a single, merged PDF file. A very easy task, right? I looked at the popular sites everyone recommends: Free Convert, PDF Candy, etc. And then I paused, and in my mind I imagined:
“How the actual hell do people trust these sites with sensitive files? It's closed source, with no privacy promises at all.”
Those forms held extremely personal information — information that could be used for malicious intent if exposed. The more I looked at these PDF websites, the more uneasy I felt. All of these tools were closed source. Privacy promises were vague. Some required holding your emails and payment information to use. I myself couldn't verify what actually happened to my files, and that was unacceptable.
So I called a friend who shared the same exact problems as me. We decided to build the PDF web app we wished existed.
Its main differentiator is that you don't need to trust what we say — you can check the code yourself in our repository.
Our non-negotiables
From day one, we chose to be different: not by cramming in every feature possible, but by committing to a few things we would not trade away.
- Confidentiality by design. We design features with 100% confidentiality in mind and avoid unnecessary data collection wherever possible.
- Everything public. Every line of code we write is public — transparency you can verify, not just trust.
- Genuinely free. No freemium model, no paywalls, no watermarks, no trials, no limited usage.
- Do the simple things better. Not focusing on adding every feature humanly possible.
Privacy isn't a feature. It's the foundation.
If you've ever hesitated to upload a document because it felt risky, you're not alone — not even a little. We literally built this for that exact reason.
Try it on the homepage, or audit the code yourself on GitHub.
An update, a year on. The project began as ZyncPDF and has since grown well past PDFs — images, audio, video, text, code and more — so it is now ZyncTools. The principle has not moved an inch: every tool still runs in your browser, and your files still never leave your device.