JSON Repair
JSONFix malformed JSON: unquoted keys, single quotes, trailing commas, comments, undefined values, and unclosed brackets
Paste JSON that's technically broken, like a hand-written config with trailing commas and single quotes, or a JSON blob an LLM wrapped in markdown fences and comments, and this attempts to fix it: quoting unquoted keys, converting single quotes to double, stripping trailing commas and comments, replacing `undefined`/`NaN`/`Infinity` with `null`, and closing unclosed brackets. It's a set of regex-based heuristic fixups rather than a real lenient JSON5 parser, so on ambiguous or badly malformed input it can guess wrong or fail outright, and the output is always worth reviewing rather than trusting blindly. This is the tool for genuinely broken JSON; if your JSON already parses fine and you just want it pretty-printed or minified, JSON Formatter is the right one instead.
How to use JSON Repair
- 1.Paste JSON copied from a log file or LLM output that has unquoted keys or trailing commas to get it auto-fixed into valid, parseable JSON.
- 2.Use it to clean up JSON-like config strings written by hand with single quotes or JS-style comments before loading them into a strict parser.
- 3.Run an LLM's raw text response through it when the model wrapped valid-looking JSON with markdown fences or added a stray comment.
Frequently asked questions
Use via API, SDK, or MCP
cURL# Free: 1,000 req/day · Pro: 10,000 req/day
curl -X POST https://api.utilix.tech/v1/tools/repair-json \
-H "Authorization: Bearer utx_live_..." \
-H "Content-Type: application/json" \
-d '{"json": "{\"name\":\"Alice\",\"age\":30,}"}'Get an API key from your dashboard · Full API docs →