Most free online PDF tools work the same way: you upload your file, a server processes it, and you download the result. For a passport scan or a bank statement, that is a lot to ask of a stranger's computer.

I built Stayput Tools, a set of 154 free PDF, image, audio and video tools where the work happens inside your browser tab. Nothing is uploaded. This post is about how that works, what it costs, and how you can check that I'm not lying.

Why not upload?

Browsers can now do most of this work themselves:

  • PDF: pdf-lib to create and edit, pdf.js to display.
  • OCR: a WebAssembly build of an OCR engine.
  • Video: WebCodecs (through the Mediabunny library) to read and re-encode video.
  • Background removal: a small neural network running through ONNX Runtime (WebAssembly).

The site is static. There is no server that could receive a file.

What it costs

Running on the user's device has real limits, and I would rather list them:

  • Video is limited to about 1 GB per file (8 GB in Compress Video and Trim Video).
  • On a phone, a long video takes roughly as long to process as it plays.
  • HEVC video needs a browser that can decode it.
  • Converting a designer-made PDF to Word is approximate.

How to check that nothing is uploaded

You do not need to trust me:

  1. Open your browser's developer tools (F12) and pick the Network tab.
  2. Use any tool on the site.
  3. Look at the requests: none of them carries your file.
  4. Or turn off your internet and use the tool again. It still works.

Each tool page also shows how many bytes it has sent: [CHECK the page and copy the exact wording].

The site also uses a Content-Security-Policy that only allows connections to itself, so even a bug could not send a file somewhere else. [Verify this is still true before publishing.]

What I learned

[Pick ONE real thing you learned, with the number you measured. Example: "Without a frame rate, the encoder assumed 30 fps, so a 60 fps video came out at twice the bitrate. Setting the frame rate fixed it (2.7 Mbps requested, 5.6 Mbps before, 2.9 Mbps after)." Write only what you actually measured.]

Try it, and tell me what breaks

It started as merge and compress and grew into the small jobs that online forms ask for: a signature under 20 KB, a photo at 3.5 × 4.5 cm, a PDF under 200 KB. It is free, with no sign-up and no watermark.

It is brand new, so I would really like to hear what breaks. Comments welcome.