The JSON validator that doesn't phone home
Catch syntax errors before they reach production.
Trailing commas, missing quotes, structural issues: all flagged with line-level precision, entirely in your browser.
Why Validate JSON?
Invalid JSON is one of the most common causes of API failures and configuration errors. A single misplaced comma or missing quote can break an entire pipeline. Our validator catches these issues before they reach production.
RFC 8259 Enforcement & Real-Time Error Detection
- Real-Time Syntax Detection: Catches trailing commas, missing quotes, and structural errors across 100MB+ payloads the instant you type, with exact line and character pinpointing. No more hunting through JSON blobs.
- RFC 8259 Enforcement: Validates strictly against the official JSON specification, guaranteeing your payloads parse correctly in any language, runtime, or browser environment.
- Silent Failure Prevention: Invalid JSON causes cryptic 500 errors and broken CI pipelines. Catch issues in-browser before they reach production, saving hours of debugging.
Privacy First: Zero-Server Architecture
Syntax errors in sensitive data are caught without external transmission.
FAQ
Why does my JSON fail validation?
The most common validation failures are trailing commas, missing quotes around property names or string values, using single quotes instead of double quotes, unescaped control characters, and duplicate keys within the same object. A validator highlights the exact line and character position of each issue.
Does the JSON validator support JSON5 or JSON with comments?
No, JSON validation follows RFC 8259 strictly, the official JSON specification. JSON5, JSONC (comments), and other supersets are not supported. However, you can use an Auto-Fix feature to repair common issues like trailing commas, and a Minifier tool can strip comments from JSONC files.
How do I validate JSON?
A JSON validator parses your input against RFC 8259 rules: matching braces, correct quoting, proper comma placement, and no trailing commas. Paste your JSON into a validator tool, and it will either confirm the structure is valid or report the exact line and character position of the first syntax error.
What does a JSON syntax error look like?
A JSON syntax error message includes the line number, character position, and a description of what went wrong. The most common errors are trailing commas, missing quotes around keys, using single quotes instead of double quotes, and unescaped control characters. Most validators highlight the exact location of the first error in your input.
Does validation check for duplicate keys?
Yes. Duplicate keys within the same JSON object are flagged as errors per RFC 8259. While some parsers silently use the last value, the validator highlights each duplicate so you can resolve ambiguity and ensure predictable behavior across all parsers.