TrustJSON — Open Source JSON Formatter

Privacy-first, open-source JSON formatter. No ads, no tracking, zero network requests. A trustworthy alternative.

TrustJSON formats JSON documents directly in your browser — locally, instantly, and with zero network requests. WHY TRUSTJSON EXISTS The most popular JSON formatter on the Chrome Web Store turned closed-source in 2026 and started injecting affiliate code and third-party tracking. TrustJSON is the open-source (MIT), auditable alternative: every line of code is on GitHub, and an automated end-to-end test proves the extension makes zero external requests. FEATURES • Automatic formatting of any JSON page (by Content-Type or .json URL) • Collapsible tree view with lazy loading — huge documents stay fast • Syntax-highlighted, readable colors in light and dark themes • Dark mode scoped to the JSON area only (never repaints the whole page) • Expand all / Collapse all / Copy / Raw view toggle • Remembers your theme preference locally • Clear error messages with line/column position for invalid JSON • Batched rendering for large arrays (no freezing) PRIVACY (the whole point) • ZERO network requests — verified by an automated test in our repository • No analytics, no tracking, no affiliate code, no ads • Your JSON data never leaves your device • The only stored preference is your theme choice (chrome.storage.local) • Fully open source under MIT: https://github.com/mundentracie/trustjson If a page fails to format, the original page is left untouched — the extension fails safe.