JSON Validator
Validate your JSON strings against the standard. Find syntax errors quickly with precise line numbers and error messages.
What is a JSON Validator?
A JSON validator checks your JSON data against the official JSON specification (RFC 8259) to detect syntax errors. JSONKit's validator provides precise line numbers and descriptive error messages so you can quickly locate and fix issues like missing commas, unclosed brackets, or invalid escape sequences.
How to use
- Paste the JSON you want to check into the editor.
- Click Validate JSON.
- If the JSON is valid, you will see a confirmation. If not, the error message shows the line and the reason, such as an unexpected token or a missing comma.
- Fix the reported problem and validate again until the document passes.
Features
- Strict validation against the JSON specification (RFC 8259).
- Precise error messages with line numbers to locate problems fast.
- Detects common mistakes such as trailing commas, single quotes, unquoted keys and unclosed brackets.
- Runs entirely in your browser, so private data stays on your machine.
Frequently asked questions
- What is the difference between JSON validation and JSON Schema validation?
- This validator checks syntax: whether the text is well-formed JSON. JSON Schema validation goes further and checks whether the data has the expected structure, such as required fields and value types. Use the JSON Schema Validator for that.
- Why is JSON with comments reported as invalid?
- Standard JSON does not allow comments. Formats like JSONC or JSON5 do, but most parsers and APIs reject them. The JSON Repair tool can strip comments and fix other non-standard syntax for you.
- Can I validate very large files?
- Yes. Validation happens locally, so the limit is your browser's memory rather than an upload size. Documents of several megabytes validate in well under a second on a modern computer.