Open your JSON in a single HTML file. The file never leaves your machine.
PrivJSON is a zero-dependency, single-file HTML app that parses, renders and searches JSON entirely in your browser — no upload, no account, no tracking, no build step.
Popular online JSON formatters were caught injecting ads and tracking into pasted data. The alternatives are either closed-source, require upload, or choke on large files. PrivJSON fills the gap: open-source + file-stays-local + offline-capable.
- Parsing off the main thread — a Web Worker reads + parses the file in the background; the page stays responsive (100 ms UI heartbeat observed during parsing in our tests)
- Lossless big integers — integer literals beyond
Number.MAX_SAFE_INTEGERare preserved exactly (e.g.9007199254740993123456789), never silently rounded - Full-dataset search — worker-side, interruptible deep search across the entire data (not just rendered rows); caps at 8M nodes / 5 s per query and says so when capped
- JSONPath copy — click any node (with Path-copy mode on) or any search hit to copy its JSONPath; one shared path function guarantees tree and search paths match; keys with spaces/dots use bracket notation (
$.users[1]["post code"]) - Zero network requests — no analytics, no CDN, no fonts, nothing. Verify: DevTools → Network → load a file → zero requests after page load. Works fully offline.
- Single
index.html— no install, no build; host anywhere or double-click locally - Demo data built in — "Load demo JSON" button lets you try everything without a file
- Parsing loads the file as text into memory first (no incremental/streaming parser in this version). A ~100 MB file wants a browser tab with ~1 GB of free memory.
- Tree rendering is bounded to 200 children per node — rendering stays fast; search still covers the full dataset.
- Deep search caps at 8M visited nodes or 5 s per query and reports when capped.
- Open the hosted page — or download
index.htmland double-click it - Drop a
.jsonfile, press Enter/Space to browse, or click Load demo JSON - Search, expand, switch to table view, copy JSONPaths — everything stays on your device
- No uploads, no analytics, no third-party requests — the page makes zero network requests after load
- The "Download offline copy" button writes a pristine app template; it never serializes the live DOM, so your data can never leak into it
- Source is ~1300 readable lines in one file — audit it in one coffee break
v0.2. Bugs & feature requests → GitHub Issues.
MIT — see LICENSE.