JSON Validator
Check if your JSON is valid instantly — get precise error messages with line numbers for fast debugging.
More JSON Tools
What is the JSON Validator?
JSON validation checks whether a string conforms to the JSON specification (RFC 8259). Unlike JavaScript object literals, JSON has strict rules: all keys must be double-quoted, no trailing commas are allowed, no comments are permitted, and only specific data types (string, number, boolean, null, array, object) are valid. This validator parses your input using the same engine browsers use internally, providing precise error messages that pinpoint the exact character position where parsing fails.
How to use the JSON Validator?
- Paste or type your JSON into the input editor below.
- The validator checks syntax in real time as you type — errors are highlighted with a red indicator showing the exact issue and line number.
- A green 'Valid JSON' badge appears when your JSON passes all syntax rules.
- Common issues detected: trailing commas, single quotes, unquoted keys, missing brackets, unescaped characters, and comments.
- Click 'Copy' to copy valid JSON or use 'Format' to pretty-print it after validation.
Frequently Asked Questions
What does a JSON validator check?
A JSON validator verifies that your text conforms to the JSON specification (RFC 8259). It checks for proper double-quoting of keys and strings, correct bracket and brace nesting, no trailing commas, no comments, properly escaped special characters, and valid data types (string, number, boolean, null, array, object).
What is the difference between JSON validation and JSON formatting?
Validation checks whether the JSON is syntactically correct according to the spec. Formatting (pretty-printing) adds indentation and line breaks to make valid JSON readable. This validator does both — it tells you if your JSON is valid and can also format it once it passes.
Why does my JavaScript object fail JSON validation?
JavaScript objects allow single quotes, unquoted keys, trailing commas, and comments. JSON does not allow any of these. Convert single quotes to double quotes, wrap all keys in double quotes, remove trailing commas after the last element, and strip all comments to produce valid JSON.
Is this validator safe for sensitive data?
Yes. All validation runs entirely in your browser using JavaScript's native JSON.parse(). Your data never leaves your device — nothing is sent to any server.