How FormFlow keeps your files on your device
"We don't upload your files" is easy to claim. This page explains how FormFlow actually works, what is stored where, and how you can check it yourself in two minutes.
The short version
- The page loads once. Your browser downloads FormFlow's HTML, styles and JavaScript from our server, like any website.
- Your file is read locally. When you choose a PDF or a photo, the browser hands its bytes to that JavaScript, inside your tab. There is no upload step and no FormFlow server that accepts documents.
- Everything is done in the tab. Rendering pages, filling fields, drawing signatures, straightening photos and text recognition all run on your own processor.
- The result is created in memory and saved by you. Download writes the new PDF from the tab to your device. Close the tab and the working copy is gone.
What runs in your browser
| Job | Open-source library | Licence |
|---|---|---|
| Displaying PDF pages, reading form answers | PDF.js (Mozilla) | Apache 2.0 |
| Writing fields, signatures and new PDFs | pdf-lib | MIT |
| Searchable text in scans (optional) | Tesseract.js | Apache 2.0 |
| Edge detection, perspective correction, B/W filter | FormFlow's own code (canvas) | — |
These libraries are loaded only after you choose a file, and they are served from FormFlow's own domain — not from a third-party CDN. The text-recognition engine and its English language data (about 7 MB) are downloaded from FormFlow the first time you tick "Make text searchable", and then cached by your browser.
What is stored, and where
| What | Where | How long |
|---|---|---|
| The document you are working on | Tab memory only | Until you close or reload the tab |
| A file passed to the next tool ("Continue with this file") | Your browser's IndexedDB storage for this site | Deleted as soon as the next tool opens it; ignored after 15 minutes |
| Saved signatures (only if you tick "Remember on this device") | Your browser's localStorage for this site | Until you press "Forget saved signatures" or clear site data |
| Your documents, photos, answers or signatures | FormFlow's servers | Never — they are not sent |
Our web server does keep ordinary access logs (IP address, page requested, time, browser), as every website does. Those requests are for pages and scripts, never for your files. Details are in the privacy policy.
Check it yourself
You do not have to take our word for it.
- Watch the network. On a computer, open your browser's developer tools (F12, or right-click › Inspect) and choose the Network tab. Open a FormFlow tool and process a PDF. You will see page scripts loading from pdfoverwk2026.com — and no request that carries your file.
- Go offline. Load a tool page, then turn on airplane mode. Open a PDF, fill or sign it, and download it. It still works, because nothing needed a server. (OCR needs to be loaded once while online.)
- Read the storage. In developer tools, Application › Storage shows exactly what FormFlow keeps in IndexedDB and localStorage.
What this means — and what it does not
Because FormFlow never has your documents, we cannot lose them in a breach, read them, or hand them to anyone. The flip side: we cannot recover a file you forgot to download, we do not send documents to other people for signature (a signing packet is something you send yourself), and we cannot provide a server-side audit trail of who signed what. For why that matters legally, see are electronic signatures legal in the US?
Your device is part of the picture too. If you are on a shared or work computer, delete downloaded copies when you are done, and avoid "Remember on this device" for signatures.