Most "free online dev tools" quietly POST everything you paste to a server. For API payloads, tokens, or customer data, that's a bad default.
A cleaner pattern: tools that do all the work client-side. The page loads once, then parsing/generating/converting happens locally — nothing is uploaded, no signup, and it works offline.
Here's a set that actually follows this. All have a free core; paid only unlocks bulk/export/history.
Runs entirely in your browser
JSONForge — format, diff, validate, infer a schema. Inspect payloads you'd never paste into a random box.
