This is a free, real-time JSON formatter and validator that runs 100% in your browser. No data is sent to any server. It supports formatting (beautifying), minifying, sorting keys alphabetically, and real-time validation with line-accurate error messages.
JSON.parse() converts your text into an in-memory JavaScript object, then JSON.stringify() renders it back with proper indentation. This also validates the JSON as a side effect " any syntax errors are caught and displayed with the exact character position.
All processing is done entirely in your browser's memory using JavaScript. No data is sent to any server. When you close this tab, the data is gone. This makes it safe to use with API keys, tokens, or private configuration files.
It recursively sorts all object keys alphabetically throughout the entire JSON structure. Useful for comparing two JSON objects for differences or enforcing consistent key ordering in config files.
Minifying removes all whitespace, newlines, and indentation from valid JSON. The result is functionally identical but smaller " useful for reducing payload size in HTTP API responses or configuration files.
Validate any JSON string for syntax errors and get precise error messages with character-level position indicators.
An online JSON validator checks whether a given string conforms to the JSON specification (RFC 8259). It detects syntax errors that would cause JSON.parse() to fail and reports the exact error location.
This validator uses the browser's native JSON.parse() engine, which means it validates JSON exactly the same way your JavaScript application will. No discrepancy between validation here and runtime behavior in your code.
Common validation errors include: trailing commas (allowed in JS but not JSON), single-quoted strings, unquoted object keys, JavaScript literals like undefined or NaN, and mismatched brackets. The tool catches all of these and tells you exactly where the problem is.
Why validating JSON prevents costly bugs:
Paste your JSON into the input pane. If valid, the "Valid" badge appears and you can click "Format" to prettify it. If invalid, the error message tells you exactly what's wrong and where — for example, "Unexpected token , at position 342" means there's a problem with a comma at character 342.
Common causes: (1) Trailing commas — remove commas before closing } or ]. (2) Single quotes — JSON requires double quotes. (3) Unquoted keys — {"name": "ok"} is valid, {name: "ok"} is not. (4) JavaScript values like undefined, NaN, or Infinity. (5) Comments — JSON does not support // or /* */ comments.
All validation runs in your browser using JavaScript's built-in JSON.parse(). Your data is never sent to any server. Other online validators often upload your JSON to their backend for processing — meaning your API keys, tokens, and configuration data pass through their servers.
JSON is a strict subset of JavaScript. Features allowed in JS but banned in JSON include: trailing commas, single-quoted strings, unquoted keys, comments, hexadecimal numbers, undefined, NaN, Infinity, and functions. JSON only supports strings, numbers, booleans, null, objects, and arrays.
This tool validates JSON syntax (is it well-formed?), not JSON Schema compliance (does it match a specific structure?). JSON Schema validation checks whether data matches a defined shape with required fields, types, and constraints. This tool focuses purely on syntax correctness.
This error means your JSON is incomplete — usually a missing closing bracket ], brace }, or quote ". Count your opening and closing brackets to find the mismatch. Deeply nested JSON often has this issue when you accidentally delete a closing character.