Developer Reference

This section collects the lookup material I reach for while building and debugging, kept on single fast pages with no popups and no pagination. The tools on this site answer "do this for me"; these pages answer "what was that syntax again". Each one is curated by hand and revised when the underlying standards move.

The HTTP Methods page settles the questions that come up in every API code review: which verbs are idempotent, which may carry a body, and what caches assume about each. DNS Records explains what every record type actually does, which pairs well with the DNS Lookup tool when a domain misbehaves. The ASCII Table lists all 128 codes with decimal and hex values, useful for escape sequences, file format debugging, and the occasional off-by-one in a parser.

The Regex Cheatsheet covers character classes, quantifiers, anchors, and lookarounds, with ready-made patterns you can try in the Regex Tester. CSS Selectors documents every selector with its specificity, including the modern :has(), :is(), and :where() forms. CSS Units explains when rem beats px and what the newer viewport units solve, and the CSS Unit Converter turns those rules into exact numbers. Git Commands is the recovery-recipe page I open when a rebase goes sideways, and the SQL sheet compares Postgres, MySQL, and SQLite behavior for joins, window functions, and CTEs.