Case Converter
Change text to upper, lower, Title or Sentence case, convert variable names between camelCase, snake_case, kebab-case and more, and clean up spaces, blank lines and full-width characters. Works line by line, updates as you type, and never leaves your browser.
Tip: once you pick a conversion, anything you type or paste on the left is converted the same way automatically. Use "Use result as input" to chain several conversions.
How to use
- Paste your text into the Input box. It can be a headline, a paragraph, or a list of variable or column names with one per line.
- Click any conversion button. The result appears on the right straight away and the active button is highlighted. Keep editing the input and the result follows, using the same conversion.
- Click "Copy result" to copy it. To apply a second step, for example removing blank lines and then converting to snake_case, click "Use result as input" and pick the next conversion.
What each format looks like
- UPPERCASE / lowercase: HELLO WORLD / hello world. Handy for normalising data typed in mixed case.
- Title Case: capitalises the main words of a headline and keeps short articles, conjunctions and prepositions (a, an, the, and, of, in, to and so on) in lower case, except when they open or close the title or follow a colon. Example: The Lord of the Rings: The Return of the King.
- Sentence case: capitalises only the first letter of each sentence and keeps the pronoun "I" upper case. Many news sites and style guides use it for headings.
- iNVERSE cASE: swaps upper and lower case, which is the quickest way to fix text typed with Caps Lock on by mistake.
- Code names: the phrase user login count becomes userLoginCount (camelCase), UserLoginCount (PascalCase), user_login_count (snake_case), user-login-count (kebab-case), USER_LOGIN_COUNT (CONSTANT_CASE) or user.login.count (dot.case).
When it helps
Make every heading in an essay, blog post or slide deck follow the same title case style. Turn an ALL-CAPS paragraph from an email or product sheet back into readable sentences. When wiring a front end to an API, rename a whole column of snake_case fields to the camelCase JavaScript expects, or go the other way for database columns. Turn a page title into a kebab-case URL slug or CSS class. Strip the double spaces and empty lines that come along when you copy from a PDF, web page or spreadsheet. Turn full-width letters and digits typed with a Chinese, Japanese or Korean input method (ＡＢＣ１２３) back into normal ASCII so search, comparisons and imports work.
Tips
- The code-name converters detect the original style for you. XMLHttpRequest, get-user-id, MAX_SIZE and first name are all split into words first, so you can convert straight from any format to any other.
- Line by line is on by default, which suits a list of field names. Turn it off to merge the whole input into a single name, which is useful for turning a sentence into one identifier.
- Title Case leaves words that already contain inner capitals alone (iPhone, NASA, McDonald). If a whole line is in capitals, it is lowered first so the rules can apply.
- Full-width to half-width also turns full-width commas and brackets into ASCII punctuation. Tick "Keep CJK punctuation" when you only want letters, digits and spaces converted.
- Sentence case lowers acronyms too (NASA becomes nasa), so check proper nouns afterwards.
How it works
Case changes use the browser's built-in Unicode case mapping, so accented and non-Latin letters such as é, ß or Cyrillic convert correctly, while scripts without case, like Chinese, are left untouched. The code-name converters split text into words at spaces, underscores, hyphens, dots and lower-to-upper case boundaries, then join the words in the target style. Full-width conversion uses the fixed one-to-one mapping between the Unicode full-width block (U+FF01 to U+FF5E) and printable ASCII, with the ideographic space mapped to a normal space.
Privacy
Every conversion runs in a small script inside your browser. Your text is not sent to a server and is not saved in local storage, so closing the tab clears it. Source code, internal field names and unpublished drafts are safe to paste.
FAQ
Q: Is my text uploaded?
A: No. All conversion happens locally in your browser, the page has no step that sends text anywhere, and it keeps working offline once loaded.
Q: What is the difference between Title Case and Sentence case?
A: Title Case capitalises every major word of a heading and keeps short function words lower case; it is common for book and article titles. Sentence case capitalises only the first word of each sentence, which reads more like normal prose and is the house style of many websites.
Q: Which words stay lower case in Title Case?
A: Articles (a, an, the), coordinating conjunctions (and, but, or, nor, for, so, yet) and short prepositions such as of, in, on, at, to, by, with and from. They are still capitalised at the start or end of a title or after a colon.
Q: What is the difference between camelCase and PascalCase?
A: Both join words and mark each new word with a capital. camelCase starts lower case (userName) and is typical for variables and functions in JavaScript and Java; PascalCase capitalises every word (UserName) and is typical for class and component names.
Q: Does it work with accented letters and Chinese?
A: Yes. Accented and Cyrillic letters change case correctly. Chinese has no case, so it is left as it is, and in code names it is treated as an ordinary word. Full-width conversion only touches full-width letters, digits, punctuation and spaces.
Q: Why did my acronyms turn lower case?
A: lowercase, Sentence case and the code-name formats normalise every letter, so acronyms like NASA or HTTP change too. Title Case keeps existing acronyms where it can; with the other formats, check proper nouns after converting.