Fix JSON Online: Repair Invalid JSON

The Five Faults Behind Most Broken JSON

1. Trailing comma — {"a": 1,} or [1, 2,]. Delete the comma before the closing bracket.
2. Single quotes — {'a': 1}. Replace every ' around keys and string values with ".
3. Unquoted key — {a: 1}. Wrap the key in double quotes.
4. Comment — // note or /* note */. Remove it, or switch the file to JSONC, JSON5, or YAML.
5. Unclosed bracket or quote — reported as an unexpected end of input. Count openers against closers from the reported line upward.

Repair Workflow

1. Paste the broken JSON. Note the reported line and column.
2. Fix that one character. Do not fix ahead — a parser stops at the first fault, so later errors are still hidden.
3. The check re-runs as you type. Repeat until the status reads valid.
4. Send the repaired document through the JSON Formatter to normalise indentation.

Smart Quotes and Invisible Characters

Text copied out of a word processor, a chat client, or a PDF often carries typographic quotes (“ and ”) that look correct but are not U+0022. A byte-order mark at the start of a file and a non-breaking space between tokens fail the same way. When the reported column looks like it points at valid text, one of these is usually why.