A JSON workbench that never uploads your data
Format, diff, repair, query and convert JSON at up to 100 MB — 100% inside your browser. No sign-up, no server, no upload.
Drop a .json file anywhere to start
Your JSON never leaves this browser
There is no backend to upload to. Parsing, diffing, repair and schema inference all run in a Web Worker on your machine. Offline works too — the whole app is a PWA.
Your JSON never leaves this browser
Honest footnote: this page loads anonymous analytics and advertising scripts. They cannot see your document, because your document never touches the network.
Everything is one click away
JSON Formatter
Pretty-print, minify and sort JSON keys. Runs entirely in your browser.
JSON Diff
Compare two JSON documents with smart array alignment that reports moves instead of 10,000 modified rows.
JSON Repair
Fix truncated, fenced, commented or single-quoted JSON from LLM output — with a line-by-line report.
JSON Schema Generator
Infer a JSON Schema (draft-07 or 2020-12) from one or many sample documents.
JSONPath / JMESPath Tester
Run JSONPath or JMESPath queries against a document, in-browser.
JSONL Viewer
Browse newline-delimited JSON line by line; bad lines never block the rest.
How we compare to json.site
Measured on a 5 MB document in Chrome 130, M1 MacBook Air.
| Capability | JSONForge | json.site / typical online tools |
|---|---|---|
| Where the JSON is processed | Your browser (Web Worker) | Uploaded to their server |
| Max file size | 100 MB | Usually 1–5 MB |
| 10,000-row array with 1 row inserted | 1 added (+ moves shown) | 10,000 modified |
| Reports moved rows | Yes — separate "moved" state | No |
| Repairs truncated LLM output | Yes, with a per-line change report | No |
| Works offline | Yes (PWA) | No |
| Sign-up / paywall | None | Often capped or paid |
FAQ
Does my JSON ever leave my device?
No. There is no backend to upload to — the entire tool is static files plus a Web Worker in your browser. You can prove it: turn off your network and every feature still works.
Then why is there advertising?
Ads and anonymous analytics do load third-party scripts, so the honest promise is "your JSON never leaves the browser" rather than "zero third-party requests". Ad scripts cannot read your document: it is never written to window, data-* attributes, or the URL.
How large a file can I open?
Up to 100 MB. Above 50 MB the editor switches to a read-only virtual viewer that renders only the visible lines; above that we point you to the CLI.
Why does diff show "moved" rows?
Because array rows are matched by a detected key (id, uuid, …) instead of by index. Reordering a 10,000-row array then reports a handful of moves instead of 10,000 modifications.