JSON Peek — JSON Viewer, Formatter, Tree & jq Filter

Fast JSON viewer & formatter. Collapsible tree, search, jq filter, JSONL support, copy path, export. Private, no tracking.

JSON Peek turns raw JSON and API responses into a clean, collapsible, syntax-highlighted tree the moment you open them — no copy-pasting into another tool. Built for developers who live in API endpoints, config files, and logs, it stays fast on huge payloads, handles the messy real-world cases other viewers choke on, and never sends your data anywhere. What's new in 1.0.2 🔢 Big-ID protection — integers beyond 2^53−1 (snowflake ids, int64 keys) are now detected and marked ≈ with a warning instead of being silently rounded. The raw view always has the exact value. 📦 Embedded JSON — stringified JSON inside JSON ("payload": "{...}") gets a one-click parse button that expands it into the tree. 🕑 Timestamp hints — hover epoch or ISO 8601 values to see the human-readable UTC and local time. 📝 Scratchpad upgrades — full collapsible tree with item/key counts (matching the main viewer), expand/collapse all, and proper light-theme support. ⚡ Fast on large files Virtualized rendering keeps scrolling, expanding, and collapsing smooth even on multi-megabyte documents with tens of thousands of nodes. Only what's on screen is drawn, so big responses don't freeze the tab. 🌳 Readable tree, instantly Collapsible objects and arrays with indent guides, item and key counts on collapsed nodes, syntax colours for every data type, clickable links, and line-level structure. Expand-all and collapse-all in one click. 🔎 Search that finds things Search keys and values at once. Matches auto-expand into view with next/previous jumping and a live match count. 🧪 jq-style filtering, built in A filter bar with a dependency-free jq subset: paths, iteration, pipes, select(), map(), keys, length, and more — e.g. .items[] | select(.id > 1). Slice a big response down to exactly what you need. 🧾 JSONL / NDJSON support Log and streaming formats where each line is its own record are detected automatically and shown as a clean array — a case most viewers miss. 🛠️ Handles broken JSON gracefully Trailing commas, comments, and single quotes are recovered with a clear note about what was fixed. Genuinely invalid JSON shows the exact line and column instead of a blank page. HTML error pages served as JSON are detected, not mangled. 📋 Copy & export Copy the whole document (pretty or minified), any value, or the exact path to a node. Export to JSON, minified JSON, or flattened CSV. 📝 Scratchpad Paste any JSON or JSONL to format, validate, and explore it — no need to open a URL. 🔒 Private by design JSON Peek runs entirely on your device. It makes zero network requests, has no analytics or tracking, and never transmits the JSON you view. Preferences are stored locally. The code is open and auditable. ⌨️ Keyboard friendly / to search, R to toggle raw view, E to expand all, C to collapse all. Perfect for: backend and frontend developers, API and QA engineers, data engineers, and anyone who opens JSON in the browser. JSON Peek is free. If it saves you time, you can support development on Ko-fi — entirely optional. JSON Peek is a product from niallcodes — an independent software project based in the United Kingdom.