Case Converter

Case conversion is one of those small tasks that eats disproportionate time when done by hand. Retyping twenty column headers into snake_case, fixing a document where Caps Lock was stuck, or turning a list of product names into URL slugs — each is a minute of tedious, error-prone editing.

Prose cases

UPPERCASE is for emphasis and, in a few conventions, for legal defined terms. Avoid it in body copy: it removes the word shapes readers rely on for fast scanning, and in most contexts it reads as shouting.

lowercase appears in design systems, brand marks and some modern style guides that reject capitalisation entirely.

Sentence case capitalises the first word and proper nouns only. It is the dominant convention for headings in technical documentation, including Google's and Microsoft's developer style guides.

Title Case capitalises principal words. It remains standard for article headlines, book titles and section headings in US publishing.

Programming cases

Word-boundary detection

The interesting part of case conversion is deciding where words begin. This tool splits on spaces and punctuation, and it also splits existing camel and Pascal boundaries — so userAccountBalance correctly becomes user account balance before being re-cased into any other convention. Without that step, converting camelCase to snake_case would produce a single unbroken token.

Digit boundaries are treated conservatively: http2Server becomes http2_server rather than http_2_server, because splitting digits from letters breaks far more identifiers than it fixes.

Unicode correctness

Case mapping is not a simple ASCII offset. German ß uppercases to SS, Turkish i has a dotted capital İ and a dotless ı, and Greek has context-sensitive final sigma. This tool uses the platform's Unicode-aware case mapping, so accented Latin, Greek and Cyrillic text converts correctly rather than producing mojibake.