Case Converter

Rescuing everyday writing

The classic emergency is realising three paragraphs into an email that caps lock was on. Select, paste here, hit Sentence case, and the damage is undone in a second — capital letters land only where sentences begin. It matters beyond accidents: sustained capitals read as shouting online, most modern interfaces default to sentence case for buttons and notices, and matching that convention makes copy feel current. Title Case is handy for headings, email subject lines and report sections where every significant word starts with a capital. One honest note: this Title Case capitalises the first letter of every word, including short prepositions like 'of' or 'the'. Strict style guides that lowercase those words need a quick manual touch-up afterwards.

Casing conventions for developers

Naming conventions differ by language and layer, and retyping identifiers is a waste of fingers. Take one plain phrase — 'user profile page' — paste it here, and every variant you need is a click away instead of a retyping exercise:

• camelCase — variables and functions in JavaScript, TypeScript, Java and most C-family code: userProfilePage.
• snake_case — Python variables, database columns and API fields that favour it: user_profile_page.
• kebab-case — CSS class names, URL paths, file names and CLI flags: user-profile-page.
• UPPERCASE — environment variables and constants: USER_PROFILE_PAGE.

Working efficiently with conversions

The transformation applies to the whole editor contents at once, so you can convert an entire document's headings, a column of database fields pasted from a spreadsheet, or a single variable name without selecting anything first. Modes can be chained too — running lowercase before snake_case guarantees a fully uniform result even if the source text was SHOUTING. Because each click replaces the text in place, keep your original in the document you copied from until you are happy with the outcome; re-pasting takes a second and nothing is ever lost permanently.

What each mode actually does

Knowing the precise behaviour avoids surprises: UPPERCASE and lowercase map every letter — including acronyms, so 'NASA IDs' becomes 'nasa ids' in lowercase mode. Title Case capitalises the first letter of each whitespace-separated word and lowercases its remainder. Sentence case lowercases everything, then restores a capital after each period, exclamation mark or question mark. camelCase strips spaces entirely, keeping the first word lowercase and capitalising the rest — which merges multi-line text into a single identifier, so convert line by line when working through lists. snake_case and kebab-case do the same but join words with an underscore or hyphen instead. InvErT cAsE swaps every letter to its opposite. Numbers, punctuation and symbols pass through untouched in every mode.