JSONKit — JSON Formatter & Validator

Auto-format JSON pages into a tree, diff two JSON docs, decode JWTs, and format API responses — all in your browser. 100% private.

Turn any JSON page into something readable — instantly, and 100% on your device. JSONKit auto-detects when you're looking at a raw JSON API response or .json file and replaces it with a clean, interactive, syntax-highlighted tree. Click any key to copy its JSON path. Search across keys and values. Decode a JWT inline. See a live keys · depth · size readout. Nothing is ever uploaded — every byte is processed locally in your browser. FOUR WAYS TO WORK WITH JSON 📄 Auto JSON page viewer Open any API endpoint or .json URL and the raw text becomes an interactive tree — collapsible, searchable, with click-to-copy paths, clickable URLs, and inline JWT decoding. Handles newline-delimited JSON (NDJSON) and JSONC-style comments/trailing commas too. 🛠 Resizable workbench Click the toolbar icon for a formatter that docks in a side panel and stays open while you browse. Format, minify, sort, validate, escape/unescape — with live validation, recent-input history (stored locally only), format-on-paste, adjustable indentation, light/dark themes, and a pop-out window. A keyboard shortcut for every action. 🔀 Local JSON diff Paste two JSON documents and get a proper line-level diff — additions and deletions clearly highlighted. Computed entirely in your browser; nothing is ever sent anywhere. 🔑 JWT decode Paste a raw JWT and decode its header, payload, and expiry instantly — no network call, no third-party decoder site. 🔍 DevTools panel Open DevTools → JSONKit. Every JSON network response is captured with method, status, and size. Filter the list, explore any response in the same interactive tree, or export the whole session as one file. 🖱 Right-click to format Select JSON anywhere on a page and choose "Send selection to JSONKit" to open it prefilled in the workbench or any tool. ONE JSON, EVERY TOOL Viewing something in the extension? Hit "Open in JSONKit" and the exact JSON opens — prefilled — in whichever tool you need on jsonkit.in: Formatter, Diff, JSON Schema Generator, JSONPath Tester, or the CSV / YAML / XML / TypeScript converters. 100% PRIVATE — BY DESIGN The extension makes zero network requests of its own and has no analytics. All JSON processing — the page viewer, the workbench, the diff tool, JWT decoding — happens entirely on your device. Paste production payloads without a second thought. FREE. NO ACCOUNT. NO ADS.