How to validate JSON
- Paste your JSON or open a file.
- Read the verdict at the top.
- If it is invalid, fix the character the pointer shows and check again.
About this tool
Paste JSON to get a plain answer: valid or invalid. A valid result also tells you the type, the number of keys, the depth and the size. An invalid result shows the line and column, a pointer under the exact character, and the reason, such as a trailing comma, single quotes, an unquoted key or a missing bracket. Repeated keys are flagged too.
Common questions
What are the most common JSON mistakes?
A comma after the last item, single quotes instead of double quotes, keys without quotes, comments, and a missing comma between items. Each of these gets its own explanation.
Does it check against a schema?
No. It checks that the text is valid JSON, not that it has the fields your program expects.
Why does it warn about repeated keys?
JSON allows the same key twice, but programs keep only the last value, which hides data. The warning shows where each repeat is.
Is it free to use?
Yes. There's no sign-up, and you can use it as often as you like.
Is my text uploaded anywhere?
No. This tool runs inside your browser, so what you enter stays on your device.
Do I need to install anything?
No. It works in your browser on a computer or a phone.