How to Fix Invalid JSON
A parser error tells you where JSON stopped making sense. Start by locating that error, make the smallest repair, then check the result before reusing it.
By Utilify team · Updated
Recognize the syntax problem
JSON requires double quotes around object keys and strings. Comments, trailing commas and Python values such as True or None are not valid JSON. A JavaScript object copied from source code can look correct while still failing a strict JSON parser.
Use the JSON Validator to find the first line and column that fails. Fix that location before chasing later errors: one missing quote or comma can make the rest of the document look wrong.
Input: {name: 'Ada', active: True, tags: ['math',],}
Output: {"name":"Ada","active":true,"tags":["math"]}Repair logs and AI output carefully
JSON Repair handles common malformed input using jsonrepair. It can remove Markdown fences, rewrite single quotes and remove trailing commas. Read the repair report and compare the output with the original: recovering syntax cannot recover values missing from a truncated response.
If the value is JSON inside a quoted JSON string, use JSON Unescape first. If the input is already valid, the formatter is the right tool for indentation; repairing it again adds no value.
Validate structure and meaning separately
Run the repaired document through the validator, then verify required fields, value types and the expected number of records. Valid JSON can still contain the wrong data. Keep a copy of the original whenever an automatic repair affects an important payload.