JSON Repair (Fix Broken JSON)

JSON breaks for small reasons: a trailing comma, single quotes, an unquoted key, a comment, Python's True and None, NaN, a code fence around it, or output that was cut off half-way. Strict parsers reject all of these. This tool reads the text leniently, repairs what it can, prints valid JSON, and lists every fix with its line number so you can check that the repair matches what the data should be. Valid JSON passes through unchanged.

How to use this tool

1. Paste the broken JSON — leftover prose, ` fences and JSONP wrappers are fine.
2. Choose indented or minified output.
3. Read the list of fixes and check the doubtful ones (for example a quote inside a string).
4. Copy the repaired JSON.

Formula

lenient read → repaired value → strict JSON (RFC 8259) → checked with a strict parser

Fixed: comments (//, /* */, #), trailing and doubled commas, missing commas between members or items, single, backtick and smart quotes, unquoted keys and text values, = instead of :, missing values (null), Python True/False/None, undefined, NaN and ±Infinity (→ null), +1, .5, 007 and hexadecimal numbers, raw line breaks in strings, invalid escapes, strings joined with +, wrappers such as ObjectId("…"), a JSON document stored inside a string, several concatenated values (→ array) and missing closing quotes, brackets and braces at the end. Large integers keep all their digits.

Example

The sample has prose and a code fence around it, a // comment, an unquoted key with a single-quoted value, Python True, a trailing comma in tags, smart quotes around "first programmer" with no comma after them, NaN, and a cut-off ending. The result is a valid object with name "Ada Lovelace", active true, tags ["math", "poetry"], note "first programmer", score null and both orders, the second closed as {"id": 2, "total": 12}.