Is it safe to paste a JWT online?

Only if the tool provably never transmits it. TokenPrism is built so you don't have to take our word: all cryptography runs in a Web Worker in your browser; a strict Content-Security-Policy makes outbound requests impossible; the app is an offline-capable PWA you can use with networking disabled; and a CI test fails the build if any core flow fires a single network request.

The article shows how to verify any JWT tool yourself with your browser's network tab — and why you should still prefer redacted or test tokens over production credentials in any online tool. Then decode your token or read the FAQ.