Free Online JSON Validator
The JSON Validator checks whether your JSON is syntactically correct and points to the exact line and column of any error. It reports the problem without reformatting your input, so it is the quick way to confirm a payload is valid.
How to use the JSON Validator
- 1 Paste the JSON you want to check into the box.
- 2 Validation runs as you type and reports the first error with its line and column.
- 3 Read the error message — it names the token that broke the grammar, not just "invalid JSON".
- 4 Fix the reported position and the check re-runs automatically until the document is valid.
How to Use
Paste your JSON and click Validate. The result tells you whether it is valid and, if not, where the syntax error is, plus useful stats like size and depth.
- Detects syntax errors and their exact position
- Shows line and column of the problem
- Reports keys, size, and nesting depth for valid JSON
- Does not reformat or alter your input
- Runs entirely in your browser
Validator vs formatter
A formatter rewrites your JSON for readability. A validator only checks correctness — use it when you just need a yes/no answer and the location of a syntax problem.
Frequently asked questions
What is the most common JSON syntax error?
A trailing comma after the last item in an object or array. It is legal in JavaScript and in JSON5, but strict JSON rejects it — and it is by far the most frequent mistake when hand-editing config files.
Does validation check my schema, or just the syntax?
Syntax only: this confirms the document is well-formed JSON. To check that the right fields exist with the right types, use the JSON Schema Generator to produce a schema and validate against it.
Why is my JSON with comments being rejected?
Comments are not part of the JSON specification. If you are editing a config file that allows them, that is JSONC or JSON5 — remove the comments before validating, or use the YAML tools instead.
Related Developer Tools
You might also need
Tools from other categories that people pair with the JSON Validator: