Dev Tools

Test regular expressions with instant match highlighting. Supports global, case insensitive, multiline, and dotall flags.

Convert cURL commands into Python requests, JavaScript fetch, and Go HTTP code instantly. Free online cURL to code generator.

Browse HTTP status codes with meanings, categories, and practical explanations. Search by code or phrase. Free online reference.

Press any key to inspect key, code, keyCode, which, location, and modifier states instantly with this online keyboard event tester.

Calculate Linux file permissions. Toggle rwx bits or enter octal codes to see symbolic and numeric equivalents.

Look up MIME / content types by file extension. Searchable list of common web and media types.

Calculate IPv4 subnet details: network address, broadcast, host count, and mask.

Convert IPv4 addresses between decimal, binary, hex, and integer. Expand and compress IPv6.

Validate card numbers with Luhn checksum and detect the card brand. Numbers never leave your browser.

Validate IBAN numbers with country-length and mod-97 checksum.

Validate email syntax and flag disposable providers. Runs client-side.