Free Online JSON Validator & Syntax Checker
Paste any JSON string to instantly validate its syntax. The validator provides detailed error messages with exact line and column numbers, making it easy to locate and fix issues. It checks for common problems like trailing commas, missing quotes, unescaped characters, and mismatched brackets. Perfect for debugging API responses, configuration files, and data interchange formats.
Common questions
What common JSON errors does the validator detect?
The validator catches trailing commas, single quotes (JSON requires double quotes), missing or extra brackets, unescaped special characters, undefined values (like NaN or undefined), and comments (not allowed in standard JSON).
Does it support JSON5 or JSONC (JSON with comments)?
This validator checks against the strict JSON specification (RFC 8259). JSON5 and JSONC extensions like comments and trailing commas will be flagged as errors since they're not valid standard JSON.