JSON Validator
Validate JSON and find syntax errors instantly. Free, no signup.
How It Works
Paste your JSON and click Validate. The tool checks for syntax errors and shows the exact location of any problems. Valid JSON is confirmed with a success message.
Common JSON Errors
Trailing commas after the last item, single quotes instead of double quotes, unquoted keys, and missing closing brackets are the most frequent JSON syntax mistakes.
| Mistake | Invalid | Valid |
|---|---|---|
| Trailing comma | {"a":1,} | {"a":1} |
| Single quotes | {'a':1} | {"a":1} |
| Unquoted key | {a:1} | {"a":1} |
| Missing comma | {"a":1 "b":2} | {"a":1,"b":2} |
| Unclosed bracket | {"a":[1,2} | {"a":[1,2]} |
Tip: Jump Straight to the Error
When JSON fails to parse, the tool reports the exact line and column of the failure. Fix that spot first, then validate again — parsers stop at the first error, so a single fix often reveals the next one. Press Ctrl+Enter (Cmd+Enter on Mac) to re-validate without reaching for the button.
Frequently Asked Questions
How do I validate JSON online?
Paste your JSON into the box and click Validate, or press Ctrl+Enter (Cmd+Enter on Mac). If the JSON is well-formed you see a green Valid JSON message. If it is not, the tool shows the parser error and the exact line and column where the problem was found.
Does the validator show where the error is?
Yes. When JSON is invalid, the tool reports the underlying parse error and calculates the line and column number of the character position where parsing failed, so you can jump straight to the mistake instead of hunting through the whole document.
What are the most common JSON syntax errors?
The frequent ones are trailing commas after the last item in an object or array, single quotes instead of double quotes, unquoted keys, missing commas between items, and missing closing brackets or braces. Any of these will make JSON fail to parse.
Does this tool check JSON against a schema?
No. It validates that your JSON is syntactically correct and parses successfully. It does not check the data against a JSON Schema or enforce required fields, types, or value rules. It confirms the structure is valid JSON.
Is my JSON kept private?
Yes. Validation uses the browser's built-in JSON parser and runs entirely on your device. Nothing is uploaded to a server, so you can safely validate confidential or sensitive JSON.