JSON Formatter and Validator — Free Online Syntax Checker
Validate JSON syntax against RFC 8259 with exact line and column error reporting. Part of the free JSON Formatter Online toolkit.
This JSON formatter and validator checks your JSON text against the RFC 8259 international standard — the same spec used by all modern browsers, servers, and APIs. Paste your JSON, click Validate, and get an instant result: a green panel with key-count and nesting-depth stats for valid input, or a red error card showing the exact line and column of every syntax mistake.
Reports line and column for every error — missing commas, trailing commas, unquoted keys, single-quoted strings, mismatched brackets.
On success, shows total object key count and maximum nesting depth — useful for understanding complex nested payloads at a glance.
Strict validation — no lenient parsing, no false positives. If it passes here, it will parse correctly in any standards-compliant JSON library.
Need to format the JSON after validating? Switch to the free JSON formatter to beautify with syntax highlighting. Or use the JSON Minifier to compress it for production.