Do You Know Where Your JWT Goes When You Paste It Into an Online Tool?

The Moment I Froze Pasting a JWT token into an online decoder. Throwing API response JSON into a formatter. Diffing code with an online tool. If you're a developer, you probably do this every day. I did too. One day, while decoding a JWT as usual, it hit me: "This token contains the user's email and role info… where did it just get sent?" I opened DevTools' Network tab. A POST request had fired. My input data was being sent to a server. No malicious intent, obviously. Server-side processing is just how it's designed. But when you think about it, it's unsettling. This experience led me to build PureMark — a developer tool suite that runs entirely in the browser. JSON / Base64 / URL / Diff / Timestamp / JWT — none of the six tools ever send your data externally. It's Already Happening — Data Leaks Via Online Tools "Am I overthinking this?" you might wonder. But incidents have already occurred. 80,000 AWS Keys Leaked (November 2025) Security firm watchTowr Labs discovered that over 80,000