What "no upload" actually means
Every tool on StuHub is implemented as a standalone JavaScript program that runs in your browser tab. When you drop a file onto an upload zone, the file is read into your device's memory using the browser's FileReader or Blob APIs, handed to a client-side library (pdf-lib, pdfjs-dist, xlsx, jsqr, tesseract.js, and so on), and the transformed result is handed back to you as a download. At no point does the file cross the network.
Why we can be specific about this
Most "free online" tool sites upload your file to their servers, process it there, and stream the result back. That forces you to trust their retention policy, their infrastructure, and their subcontractors. With StuHub there is no server to trust — there is no endpoint that accepts your files. If our servers disappeared tomorrow, every tool here would continue to work exactly the same.
How to verify it yourself
- Open your browser's DevTools (F12) → Network tab. Drop a large file onto any tool. You will see zero outbound requests for the file itself — only the tool's JavaScript bundle loading once.
- Turn off your network connection after the tool's page has finished loading. Every tool that does not fetch live rates (the currency converter is the only exception) continues to work offline.
- The site is built on a small, auditable stack. You can read every line of code for every tool in the public repository.
What we do collect
Anonymous event-level analytics (which tool was opened, whether a success event fired) and aggregate rating counts — never file contents, file names, or anything derived from what you paste or upload. See Privacy for the exact list.