JSON Validierer

What is JSON Validierer?

A JSON validator checks whether a string is well-formed JSON according to RFC 8259. Valid JSON uses double-quoted strings, supports objects, arrays, numbers, booleans, and null, and disallows trailing commas and comments. The validator parses the input and reports either success or a precise error — including the line, column, and a human-readable reason — so the user can fix the problem at its source.

How It Works

The tool attempts JSON.parse on the input string. If parsing succeeds, the input is valid and the tool reports the parsed structure's type and size. If parsing throws a SyntaxError, the error message is parsed to extract the character offset, which is converted to a line and column number for display. A lenient mode may optionally accept JSON5 (single quotes, trailing commas, comments) but strict mode follows the RFC.

Common Use Cases

• Checking API request bodies — confirm a payload is valid before sending it to a server
• Validating config files — catch syntax errors in JSON configuration before deployment
• Debugging parse failures — locate the exact position of a missing comma or unquoted key
• Linting data exports — verify that a generated JSON file is structurally correct

Technical Details

Standard: RFC 8259 (strict JSON). Disallowed: trailing commas, single-quoted strings, comments, unquoted keys, NaN/Infinity. Error reporting: character offset converted to 1-based line and column. The validator does not check schema conformance (use JSON Schema for that). Maximum input size is bounded by browser string/memory limits.