Developer Toolkit by Zase: JSON, JWT, Regex & More

Developer tools that run entirely in your browser. Free, fully offline and private: nothing you paste ever leaves your device.

Your browser is where you do your work, so the tools you use every day should live there too. Whatever the job, it is probably already here. Format and validate the data in front of you, decode a token to see what is inside it, test a pattern before you trust it, or generate the password, code or schedule you need and move on. The everyday text, encoding, color and conversion jobs are covered too, along with quick references for the small things you should never have to search for. And the toolkit keeps growing, with new tools added regularly. It is built to feel like a real app, not a cramped little popup. Open it in its own resizable window or dock it in Chrome's Side Panel. Choose a light, dark or system theme, pin the tools you use most as favorites, and reach anything instantly with search, a command palette, the keyboard, or a right click on selected text. Every tool is designed the same calm way, so once you know one, you know them all. It even opens where you left it, the way a tool you rely on should. Most importantly, it respects your data. Every tool runs entirely in your browser: no accounts, no analytics, no network requests, nothing uploaded anywhere. Paste a token, a key or a private snippet, and it never leaves your machine. Install it, pin it, and retire the dozen ad filled utility sites for good.