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Validate JSON, XML, YAML, CSS, JavaScript, and more
Validate JSON syntax and catch parse errors instantly. Paste JSON and get immediate feedback on structural issues, missing commas, and unquoted keys.
Validate JSON5 syntax — the relaxed JSON superset that allows comments, trailing commas, and unquoted keys. Instantly check JSON5 files for parse errors.
Validate XML syntax and catch well-formedness errors quickly. Paste XML and get instant feedback on missing tags, unclosed elements, and malformed attributes.
Validate YAML syntax online and catch indentation and structure errors instantly. Paste YAML config files and get detailed error messages with line numbers.
Validate TOML syntax online, catch parse errors quickly, and inspect normalized config output for app settings and package files.
Validate CSS syntax online and catch parse errors in stylesheets with instant feedback for malformed rules and blocks.
Validate JavaScript syntax online and catch parse errors, missing brackets, and malformed statements with instant feedback.
Validate credit card numbers with the Luhn algorithm and detect card type online without storing the number you enter.
Parse, validate, and format phone numbers by country with E.164, international, national, and RFC3966 output.
Score password strength with length, character variety, repeated-pattern checks, and practical suggestions for safer credentials.
Test Java-style regular expressions with ECMAScript-equivalent matching and group capture
Validate tsconfig.json structure, flag unknown options, and surface common misconfigurations
