Case Converter

What each case does

• UPPERCASE and lowercase change every letter, using Unicode rules so accented and non-Latin letters convert correctly.
• Title Case capitalises the first letter of each word except short function words — a, an, and, as, at, but, by, for, in, nor, of, on, or, per, the, to, up, via and vs — unless they are the first or last word or follow a colon, dash or end punctuation. Hyphenated parts are capitalised too (Well-Known).
• Sentence case lowercases the text, then capitalises the first letter of each sentence and the pronoun "I".
• camelCase, PascalCase, snake_case, kebab-case and CONSTANT_CASE split the text into words — at spaces, punctuation and existing case changes such as "parseHTML" — and rejoin them in the chosen style.
• aLtErNaTiNg case flips every other character, mostly for jokes and memes.

Worked examples

Example 1: a headline

"the lord of the rings: the return of the king" becomes The Lord of the Rings: The Return of the King. "the" after the colon is capitalised because it starts a subtitle.

Example 2: a variable name

"XMLHttpRequest parse value" splits into xml, http, request, parse, value, giving xmlHttpRequestParseValue in camelCase, xml_http_request_parse_value in snake_case and XML_HTTP_REQUEST_PARSE_VALUE in CONSTANT_CASE.

Example 3: fixing caps lock

"HELLO WORLD. THIS IS I." in Sentence case is Hello world. This is I.

How to read the result

Every case appears in its own box, updated as you type. Press Copy beside the one you need; if your browser blocks clipboard access, select the text in the box and copy it manually. Line breaks are kept in the text cases; the programmer cases join everything into a single identifier.

Title case style guides

There is no single correct title case. The Chicago Manual of Style lowercases articles, coordinating conjunctions and prepositions regardless of length; AP style capitalises any word of four letters or more, including prepositions such as "with" and "from"; APA capitalises words of four letters or more and lowercases shorter minor words. This converter uses a simple list of short words that most guides lowercase, so it matches the common cases but will not resolve every judgement call. Review titles for publication against the guide your editor or publisher uses.

Acronyms and proper nouns

Title, Sentence and the programmer cases start by lowercasing, so acronyms and names lose their capitals: "NASA launches on Monday" becomes "Nasa launches on monday" in sentence case. That is unavoidable without a dictionary of names, so fix them by hand after converting. UPPERCASE and lowercase are fully reversible only in the sense of letters; the original mixed case cannot be recovered once lost, so keep a copy of the source text.

Programmer naming conventions

Different languages and teams favour different identifier styles. JavaScript and Java use camelCase for variables and PascalCase for classes; Python uses snake_case for functions and variables and CONSTANT_CASE for constants; CSS classes, URLs and file names often use kebab-case. Converting a plain-English phrase such as "total order count" into the right style saves typing and avoids inconsistent names. Digits stay attached to the word before them, so "html5 parser" becomes html5Parser.

Common uses and privacy

Writers use a case converter to fix text typed with caps lock on, to format headings consistently, and to tidy titles copied from other sources; marketers use it for ad headlines and email subjects; developers use it to rename variables, API fields and database columns. All conversion happens in your browser and the text is never sent or stored. To count the result's characters against a limit, paste it into the character counter, or check length in words with the word counter.

Case and readability

Long passages in capital letters are harder to read than mixed case, because the distinctive shapes of lowercase letters with ascenders and descenders help the eye recognise words. All-caps text also reads as shouting in emails and messages. Sentence case is increasingly preferred for interface labels, buttons and headings by many design systems because it is easier to scan and avoids arguments over which words to capitalise. Title case remains standard for book, film and article titles in much American publishing. Whichever you choose, consistency across a document or product matters more than the choice itself, and a converter makes it easy to bring stray headings into line.

Turning phrases into slugs and file names

Kebab-case is the usual format for URL slugs and many file names because hyphens are treated as word separators by search engines and are safe in web addresses. Converting "Ten Tips for Better Sleep!" gives ten-tips-for-better-sleep, with punctuation removed. Snake_case is common for database columns and data files, where hyphens can be mistaken for minus signs. Avoid spaces in file and folder names destined for the web or for scripts, since they need escaping.