JSON Validator
Validate JSON documents against strict RFC 8259 rules and inspect structure diagnostics locally in your browser.
Ready. Paste JSON and click "Validate JSON" (or press Ctrl+Enter).
Status
Ready
Root Type
—
Max Depth
—
Object Keys
—
Payload Size
0 B
About the JSON Validator
The API Toolkit JSON Validator checks whether a payload conforms to the official RFC 8259 JSON specification. When a syntax error is detected, it reports a clear message with 1-based line and column coordinates so you can fix malformed payloads immediately.
Supported JSON Values
- Composite Roots: Objects (
{"key": "value"}) and Arrays ([1, 2, 3]). - Primitive Roots: Strings (
"hello"), Numbers (42,-3.14), Booleans (true,false), andnullare all valid RFC 8259 JSON documents.
Common Syntax Errors
- Trailing commas after the last property in an object or array.
- Single-quoted strings or unquoted property names.
- Unescaped control characters (such as raw tabs or newlines) inside strings.