Overview
The JSON Validator checks whether a JSON string is syntactically valid, highlights the exact location of any errors with line and column numbers, and formats the validated JSON with configurable indentation. It also provides a structural overview showing key count, array count, nesting depth, and total character count — making it an essential debugging tool for developers working with APIs and configuration files.
How to Use
Paste or type your JSON into the input textarea. Validation runs automatically as you type with a 300ms debounce. A green checkmark and ‘Valid JSON’ banner appear for correct input; a red error banner shows the specific problem (e.g., ‘Unexpected token at line 3, column 12’). Use the Format button to pretty-print with 2-space or 4-space indentation. Minify compresses the JSON to a single line. The stats panel shows structure metrics. Copy exports the formatted result.
Background & ContextJSON (JavaScript Object Notation) was formalized by Douglas Crockford in the early 2000s based on a subset of JavaScript syntax. Despite widespread use, JSON has notable limitations: it does not support comments, does not distinguish between integers and floats (all numbers are floating-point), and cannot represent undefined values. JSON5 is an unofficial extension that adds comments and trailing commas. The official MIME type for JSON is application/json, and the file extension is .json. Malformed JSON is one of the most common sources of API integration bugs.
