JSON Formatter

Format any JSON page: syntax highlighting, collapsible tree, error detection and clickable URLs. Fast and lightweight.

Make every JSON page instantly readable. JSON Formatter automatically turns raw, unreadable JSON responses into clean, syntax-highlighted, explorable data — with a collapsible tree, error detection, and clickable links. It works on any JSON page no matter the URL, and stays completely out of the way on normal pages. FEATURES • Three views, switchable on the page — Formatted (pretty + syntax highlighted), Tree (collapsible, with indent guides), and Raw (untouched source). • Collapsible tree with indent guides — expand and collapse objects and arrays, or use Expand all / Collapse all. Large documents render lazily so it stays fast. • Error detection — invalid JSON shows the parser message and highlights the exact line so you can spot the problem immediately. • Syntax highlighting — keys, strings, numbers, booleans and null are colour-coded for fast scanning. • Clickable URLs — http(s) values become links that open in a new tab. • Works on any JSON page — detection is by response content type, not the URL, so it formats APIs, endpoints and .json files alike. • Dark mode — choose Light, Dark, or Match browser/system in the settings. It follows your system theme automatically. • Copy & Download — copy the formatted JSON or download it as a .json file in one click. • Fast and private — everything runs locally in your browser. Nothing is uploaded, and there is a negligible (sub-millisecond) impact on non-JSON pages. HOW TO USE Just open any URL that returns JSON — the page is formatted automatically. Use the toolbar at the top to switch between Formatted, Tree and Raw, expand/collapse the tree, copy, or download. Click the extension icon for the dashboard, and open Settings to pick your theme and default view. PRIVACY This extension does not collect, store, or transmit any data. All formatting happens locally in your browser. It requests only the permissions needed to read the JSON on the page you are viewing and to save your settings.