JSON Validator
Paste your JSON to instantly check if it's valid and locate any syntax errors.
About JSON Validator
This tool checks whether your JSON is syntactically valid according to the JSON specification (RFC 8259). It highlights the exact line and position of any errors, making it easy to fix malformed JSON. Everything runs in your browser — no data is sent to any server. Once your JSON is valid, use the JSON Formatter to beautify it or the JSON Minifier to compress it.
Frequently Asked Questions
What makes JSON invalid?
Common causes: missing quotes around keys, trailing commas, single quotes instead of double quotes, unescaped special characters, or mismatched brackets and braces.
Is my data safe?
Yes. All validation runs entirely in your browser. No data is ever sent to a server.
What JSON spec does this follow?
This validator follows RFC 8259, the current JSON standard. Comments and trailing commas are not valid JSON per this spec.
How do I check if JSON is valid online?
Paste your JSON into the input panel on the left — validation runs automatically. If your JSON is invalid, the exact error line and column number are highlighted in the gutter and shown in the result panel.
How do I validate JSON in Python?
Use json.loads() inside a try/except block. If it raises a json.JSONDecodeError, the JSON is invalid. For quick browser-based validation without writing code, use this tool.