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Case converter
Thirteen conversions, with title case that follows actual style-guide rules rather than capitalising everything.
Title case is a style decision, not a rule
Most case converters implement title case as "capitalise the first letter of every word." No style guide actually says that. Every major guide lowercases certain short words unless they fall first or last in the title, and they disagree about which words qualify.
AP style lowercases articles, coordinating conjunctions and prepositions of three letters or fewer. Chicago lowercases all prepositions regardless of length, along with articles and coordinating conjunctions. The practical result is that the same headline is capitalised differently depending on which guide you are writing for.
| Style | Result |
|---|---|
| Naive converter | The Guide To SEO For Small Businesses |
| AP | The Guide to SEO for Small Businesses |
| Chicago | The Guide to SEO for Small Businesses |
Hyphenated compounds are the other place converters fail. "state-of-the-art" should become "State-of-the-Art" — the first element capitalised, minor words inside the compound left alone. Splitting only on spaces gives you "State-of-the-art", which is wrong in both AP and Chicago.
Sentence case, and why lowercase first is wrong
Sentence case means capitalising the first word of each sentence and leaving the rest alone. The naive implementation lowercases everything and then capitalises character zero, which destroys proper nouns and gives you one capital across an entire multi-sentence paragraph.
This tool segments the text into sentences using Unicode sentence-boundary rules, then capitalises the first letter of each. That handles abbreviations like "e.g." and "Dr." far better than splitting on full stops, and it works for Devanagari danda (।) and other non-Latin sentence terminators. The standalone English pronoun "I" is restored afterwards.
Proper nouns are still a genuine limitation: no offline tool can reliably tell that "paris" should be "Paris" without a named-entity model, and running one would mean sending your text to a server. The honest answer is that sentence case gets you most of the way and you check the nouns.
Programmer cases
The developer conversions — camelCase, PascalCase, snake_case, CONSTANT_CASE, kebab-case, dot.case — all work by tokenising the input first rather than just replacing separators. That means myXMLParser tokenises to my / XML / Parser and converts to my_xml_parser, instead of the my_x_m_l_parser that a character-level approach produces.
- camelCase — JavaScript variables and functions
- PascalCase — classes and React components
- snake_case — Python, Ruby, SQL columns
- CONSTANT_CASE — environment variables and constants
- kebab-case — URLs, CSS classes, file names
Common questions
What is the difference between title case and capitalise each word?
Capitalise Each Word capitalises everything. Title case follows a style guide, which lowercases short articles, conjunctions and prepositions unless they are the first or last word. "The Guide to SEO for Small Businesses" is title case; "The Guide To SEO For Small Businesses" is not.
Which title case style should I use?
AP style for journalism, press releases and most web headlines. Chicago for books, academic writing and formal publishing. If nobody has told you, AP is the safer default for online content.
Will sentence case break my proper nouns?
It can. Sentence case lowercases the text before recapitalising each sentence start, so names of people and places lose their capitals. No offline tool can reliably identify proper nouns without a language model, and running one would mean sending your text to a server. Check names afterwards.
Does it handle hyphenated words correctly?
Yes. "state-of-the-art" becomes "State-of-the-Art" — the leading element capitalised and minor words inside the compound left lowercase, which is what AP and Chicago both specify.