Letter Case Converter
Convert any text into UPPERCASE, lowercase, Title Case, Sentence case, camelCase, snake_case, kebab-case, or aLtErNaTiNg case — instantly, no signup.
How to use the case converter
Paste or type your text into the box above, then click any case button. The text in the editor is replaced with the converted version, ready to copy. Conversion happens in your browser — no upload, no server round-trip.
The 11 case styles, with examples
| Case | Example | Used for |
|---|---|---|
| UPPER CASE | HELLO WORLD | Headlines, acronyms, emphasis |
| lower case | hello world | URLs, casual writing, brand voice |
| Title Case | Hello World | Headings, book titles (AP style) |
| Sentence case | Hello world | Body copy, modern UI labels |
| aLtErNaTiNg | hElLo WoRlD | Sarcasm, the SpongeBob meme |
| iNVERSE | hELLO wORLD | Caps Lock-stuck recovery |
| camelCase | helloWorld | JavaScript, Java variable names |
| PascalCase | HelloWorld | Class names in C#, Python, TypeScript |
| snake_case | hello_world | Python, Ruby, database column names |
| kebab-case | hello-world | URLs, CSS class names, file names |
| CONSTANT_CASE | HELLO_WORLD | Environment variables, constants |
| dot.case | hello.world | i18n keys, namespaces, config paths |
Each case style as its own dedicated tool
This master converter does all 12 styles in one place. If you want a dedicated single-action page (faster to bookmark, share, or link to), each style has its own:
- UPPERCASE Converter
- lowercase Converter
- Title Case Converter
- Sentence case Converter
- aLtErNaTiNg cAsE Converter
- Swap Case (iNVERSE) Converter
- camelCase Converter
- PascalCase Converter
- snake_case Converter
- kebab-case Converter
- CONSTANT_CASE Converter
- dot.case Converter
Title Case rules
Title case looks simple — capitalise the important words — but the rules vary by style guide. The most common conventions:
- Capitalise: the first and last words; all nouns, pronouns, verbs, adjectives, adverbs.
- Lowercase: articles (a, an, the); coordinating conjunctions (and, but, or, for, nor); short prepositions (to, in, on, at, of, by, up, for).
- Style differences: AP capitalises prepositions of 4+ letters; Chicago capitalises all prepositions; APA capitalises words of 4+ letters.
Our default Title Case follows the AP style. If you need a different convention, edit manually after conversion.
When each case matters
- URL slugs: kebab-case is the universal default (and the only case that's safely searchable).
- JavaScript variables: camelCase by convention.
- Python variables: snake_case by PEP-8.
- CSS classes: kebab-case.
- Environment variables: CONSTANT_CASE — POSIX requires uppercase.
- Email subject lines: Sentence case — modern, casual; reads as a person, not a headline.
- Article headlines: Title Case for traditional, Sentence case for modern.
Frequently asked questions
Does the case converter handle non-English characters?
Yes. Accented letters (é, ñ, ü), Cyrillic, Greek, and other Unicode-supported alphabets all convert correctly using JavaScript's locale-aware case mapping.
What's the difference between Title Case and Sentence case?
Title Case capitalises the first letter of every important word ("How to Write a Blog Post"). Sentence case capitalises only the first word and proper nouns ("How to write a blog post"). Modern editorial style trends toward sentence case.
Why doesn't camelCase have a space?
By convention, identifiers in code can't contain spaces. camelCase, PascalCase, snake_case, and kebab-case all encode "a multi-word phrase used as a single identifier" — different languages and contexts pick different separators.
Is there a case that preserves URL safety?
kebab-case (hyphens) is the URL-safe default. snake_case (underscores) also works in URLs but search engines treat hyphens as word separators and underscores as part of the word, so kebab-case is preferred for SEO.
Can the converter undo case changes?
Press Ctrl+Z (Cmd+Z on Mac) inside the textarea to undo the last conversion — the browser keeps standard text-edit history.
Does Title Case follow AP, Chicago, or APA rules?
Our Title Case follows AP style: capitalise prepositions of 4+ letters. For strict Chicago or APA, edit manually after conversion.