What is a JSON Validator?
A JSON validator checks whether a piece of text is syntactically correct JSON according to the official spec (RFC 8259). It's the fastest way to find a typo — a stray comma, a missing quote — that's breaking your API request, config file, or test fixture.
How to use this JSON validator
- Paste your JSON into the left-hand box.
- Click Validate JSON.
- If it's valid, you'll see a summary of the structure (keys, arrays, size). If it's invalid, you'll see the exact line and column of the first error.
Frequently asked questions
What makes JSON invalid?
The most common causes are trailing commas after the last item, using single quotes instead of double quotes, unquoted object keys, missing or extra brackets/braces, and unescaped control characters inside strings.
Does this validator check against a JSON Schema?
No, this tool checks pure JSON syntax validity (is it well-formed JSON at all). If you need to validate JSON against a specific schema's rules and data types, use our JSON Schema Validator instead.
Is there a size limit?
No artificial limit — validation happens locally in your browser, so it depends only on your device's memory.