How to Fix Common JSON Errors (Free Validator)

"Unexpected token" with no clue where to look is the worst kind of error. Paste your JSON into a validator that shows the exact line and column, fix the flagged spot, and move on.

Use the free tool: Validate JSON — errors shown with line, column, and character position.

The 5 errors you'll see most

1. Trailing comma — a comma after the last item. JSON forbids it (JavaScript allows it, which is why it's so common).

{ "name": "Ada", "role": "dev", }

2. Missing comma — two values with nothing between them.

{ "name": "Ada" "role": "dev" }

3. Unquoted or single-quoted keys — keys must use double quotes.

{ name: "Ada" }      // wrong
{ 'name': "Ada" }    // wrong
{ "name": "Ada" }    // right

4. Mismatched brackets — an opened [ closed with }, or a missing closer. Count your openers and closers.

5. Comments or undefined — // comments, /* */, undefined, and trailing text are not valid JSON, even if your editor tolerates them.

Steps to validate

1. Open the JSON Validator.

2. Paste your JSON into the editor.

3. Read the error: it reports line, column, and character position — e.g. "Line 4, Column 12".

4. Fix that exact spot (usually one of the five errors above) and re-paste until it validates.

5. Once valid, head to the JSON Formatter to pretty-print or minify it.

Troubleshooting

• Error position points at the end of the file? That usually means an unclosed bracket or quote earlier — the parser only noticed at the end. Check your openers.
• Copied from docs with smart quotes? Word processors turn " into curly quotes, which JSON rejects. Retype them as straight quotes.
• Huge minified blob? Validate first, then format — debugging one-line JSON by eye is miserable.

Next steps:

• Format, minify, and sort JSON
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