Your JSON never leaves your machine

A developer has launched jsonkit.tools, a collection of 24 browser-based developer tools for JSON formatting, validation, conversion, and more, all running client-side with no signup or upload. The project also includes api.jsonkit.tools, offering 28 endpoints with deterministic transformations for automation and LLM agents, built with Astro and vanilla JS for fast, indexable pages.

I keep a tab with a JSON formatter open roughly 300 days a year. And roughly 300 days a year, that tab tries to sell me something. So I built jsonkit.tools https://jsonkit.tools — 24 browser-based dev tools under one roof. The browser tools run client-side. No signup, no upload. You paste, you get the result. JSON formatter with tree view, validators, converters between JSON/CSV/YAML/XML both directions , Base64 and URL encoding, JSON diff, JSON-to-TypeScript, UUID and hash generators, and a timestamp converter. Each tool is its own page with its own URL — no SPA tab-switching. Most browser tool sites stop at the browser. I added api.jsonkit.tools https://api.jsonkit.tools — 28 endpoints with the same operations you get in the UI. The endpoints follow the same input/output contract. Why? Because if you're building automation or working with LLM agents, you want deterministic transformations — not a model guessing how to reformat your payload. One HTTP call, stable output, no surprises. curl -X POST https://api.jsonkit.tools/v1/json/format \ -H "Content-Type: application/json" \ -d '{"input": "{\"a\":1,\"b\":2}", "indent": 2}' Astro with static generation. Each tool compiles to its own HTML page — fast to load, easy for search engines to index, and with zero client-side routing overhead. Dark theme by default. The tools themselves are vanilla JS components. No heavy framework runtime, no hydration penalty for what is essentially a text box and a function call. jsonkit.tools https://jsonkit.tools — feedback welcome.