Developer tools

Small utilities, clear output.

Focused browser tools for common data and CSS tasks. No uploads, accounts, or third-party processing.

JWT Expiry Calculator

See if a token has expired, time left and lifetime; convert exp, iat and nbf.

Map common extensions to MIME types and reverse-lookup extensions.

Search every registered code: meaning, caching, retry and typical fix.

Octal, symbolic and checkbox permissions with the chmod command.

Edit key/value rows without losing duplicate keys or order.

Find malformed records by line and convert arrays to or from JSON Lines.

Escape text into a JSON string literal and reverse it with error position.

Run RFC 9535 queries and see every match with its normalized path.

Build responsive clamp values in px or rem with a live preview.