TL;DR — Many "online calculators" send your input to a server. CompuTools runs CRC, JWT decode, file hashing, and more entirely in the browser (Rust → WebAssembly where it matters).
Originally published on CompuTools. Try: CRC Calculator · JWT Tool · File Hash.
When you're using an online dev tool, you've probably had this thought at least once: "This site isn't sending my JWT token off to some server, right?" That's a fair thing to wonder. Most web-based encoders, decoders, and calculators send whatever you paste into them to an external server for processing. Open the network tab and check — you might be surprised how many tools do exactly that.
This post uses CompuTools's browser-based dev tool suite as a jumping-off point to explain how WebAssembly (WASM) has changed the way online calculators work, and what that actually means in practice. This isn't a usage manual — it's about the technology itself and how to make better decisions when choosing tools.
What "Processed in the Browser" Actually Means
