Most "online PDF tool" sites work the same way: you drop a file into a box, it uploads to a server somewhere, gets processed, and a download link comes back. That's simple to build, but it means a copy of your file — your tax return, your contract, your passport photo — sits on someone else's infrastructure, even if only for a few seconds.
FileKit doesn't do that. Every tool, from Merge PDF to the QR Code Generator, runs entirely inside your browser using JavaScript. There is no upload step, because there is nowhere to upload to — no database, no API, no server-side processing of your files at all.
What that actually buys you
Nothing to leak. A server that never receives your file can't log it, cache it, get breached, or have its retention policy change on you. The file goes from your disk, through your browser's memory, back to your disk.
No upload wait. Skipping the round-trip to a server means processing starts the instant you drop a file in, and a 200MB PDF isn't throttled by someone else's bandwidth cap.
Works offline. Once the page has loaded, most tools keep working even if you lose your connection — there's no server call left to fail.
The trade-off, honestly
Browser-only processing isn't free. It means we can't run heavyweight server tools like Ghostscript for PDF compression — see our PDF compression page for exactly how we work around that with in-browser rasterization instead. It also means very large files are limited by your device's own memory rather than a server's, which is usually a higher ceiling, but not an infinite one.
We think that trade-off is worth it for the kind of files people actually run through tools like this: contracts, IDs, screenshots, personal photos — exactly the things you'd rather not hand to a stranger's server, even for a second.