HOW IT WORKS
Paste JSON → Auto-validate → See exact error location with line numbers. Perfect for debugging API responses, config files, and data exports.
WHAT IS JSON VALIDATION?
JSON Validation checks if your JSON syntax is correct according to the JSON specification (RFC 8259). Even a single missing comma or quote can break your entire application.
Why validate? JSON errors are silent killers - APIs return 400/500 errors, config files fail to load, data imports crash. This tool shows you exactly where the error is (line number + description) so you can fix it in seconds instead of hunting through hundreds of lines.
Common scenarios: Copied JSON from API documentation but it has trailing commas • Exported data from Excel/database with invalid escaping • Hand-edited config file and forgot a closing bracket • Copy-pasted from JavaScript (which is more lenient than JSON).
COMMON JSON SYNTAX ERRORS
Trailing commas: {"a": 1, "b": 2,} - Last item can't have a comma. Works in JavaScript, fails in JSON.
Single quotes: {'name': 'Alice'} - Must use double quotes. {"name": "Alice"} is correct.
Unquoted keys: {name: "Alice"} - Keys must be quoted: {"name": "Alice"}.
Missing commas: {"a": 1 "b": 2} - Need comma between items: {"a": 1, "b": 2}.
Comments not allowed: JSON doesn't support // or /* */ comments. Remove them or use a "_comment" key.
Control characters: JSON strings can't contain unescaped newlines/tabs. Use \n and \t instead.
JSON VALIDATION BEST PRACTICES
Validate before deployment: Always validate JSON config files (package.json, tsconfig.json, etc.) before committing to Git. A single syntax error can break your entire build.
Use strict parsers: Never use eval() to parse JSON - it can execute malicious code. Always use JSON.parse() (JavaScript), json.loads() (Python), or equivalent safe parsers.
Handle parse errors gracefully: In production code, wrap JSON parsing in try-catch and provide meaningful error messages to users. Don't let the app crash on invalid JSON.
Validate API responses: Don't assume external APIs always return valid JSON. Validate and check structure/types before using data in your application.
Escape special characters: When generating JSON programmatically, use built-in serialization functions (JSON.stringify, json.dumps) instead of string concatenation. They handle escaping automatically.
JSON VS JSONC VS JSON5
JSON (Standard): The original specification (RFC 8259). Strict rules - no comments, no trailing commas, no single quotes. This is what APIs and most tools expect.
JSONC (JSON with Comments): Used by VS Code, ESLint, and some config tools. Allows // and /* */ comments. Still requires double quotes and no trailing commas. Example: tsconfig.json, .eslintrc.json.
JSON5: More lenient superset - allows trailing commas, single quotes, unquoted keys, comments, and more. Rarely used outside of config files. Not compatible with standard JSON parsers.
Which to use? Stick with standard JSON for APIs and data exchange. Use JSONC for human-edited config files if your tool supports it (VS Code settings, TypeScript config). Avoid JSON5 unless you have a specific reason.