JSON Validator

Validation checks that the text is syntactically correct JSON — that every string is quoted, brackets are matched, commas are placed correctly, and no trailing commas appear. Formatting (beautifying) takes valid JSON and applies consistent indentation and line breaks. This tool does both: it validates first, then shows formatted output if the JSON is valid.

JavaScript's JSON parser gives errors like "Unexpected token" at a character position. The most common causes are: trailing commas after the last item in an array or object (not allowed in JSON); single quotes instead of double quotes for strings and keys; unquoted keys; comments (JSON has no comment syntax); and values like undefined, NaN, or Infinity (not valid JSON). This validator shows the exact line and column to help you find the problem.

JSON Schema is a vocabulary for describing the structure and constraints of JSON data. You define rules — for example, that a field must be a string with at least 3 characters, or that an object must have certain required keys — and the validator checks your data against them. This tool supports a useful draft-07 subset: type, required, properties, minLength, maxLength, pattern, minimum, maximum, enum, const, items, minItems, maxItems, uniqueItems, allOf, anyOf, and not.

The type tree shows the data type of every value in your JSON — string, number, boolean, null, object (with key count), or array (with length). It is useful for quickly understanding the shape of an API response or data file without reading all the values. Nested objects and arrays are shown indented, up to 4 levels deep.

No. All processing — validation, schema checking, type inspection, syntax highlighting — runs entirely in your browser using JavaScript. Your JSON never leaves your device, making it safe to use for API responses, configuration files, tokens, or any data you would rather not send to an external service.