Format, validate, convert and decode JSON like a scientist. A fast, offline-first desktop tool built for developers.
Format, convert and validate JSON in seconds — no setup, no internet, no friction.
From quick formatting to deep format conversion — JSONLab handles it without any setup, login, or internet connection.
Paste any JWT and instantly see the header, payload and signature decoded — with human-readable timestamps, expiry status and claim descriptions. No network calls. Ever.
The search bar scans every saved entry — not just names, but every key and value nested at any depth. Match badges tell you exactly where the hit was found.
JSONLab is completely free to use. If it saves you time, consider supporting its development so we can keep building great tools for developers.
Free to use, offline-first, no login required. Works on Windows, macOS and Linux.
Free for everyone · No login · No internet required · Works on Windows & macOS
From TheHobbyist
All free, offline-first desktop apps — no subscriptions, no accounts
Choose the version that matches your Mac.
Apple menu → About This Mac → check Chip or Processor