What a case converter does and when you need one
A case converter takes whatever text you paste in and rewrites the capitalization for you. Instead of retyping a sentence because Caps Lock was on, or hunting through a heading to capitalize each word by hand, you click one button and the tool reshapes the letters. Everything on this page runs in your browser, so your text never leaves your device. Paste, pick a style, copy the result.
The reason a small tool like this earns a permanent spot in your toolbar is that capitalization is fiddly and rule-bound. English headings follow conventions that are easy to get wrong, and code has its own naming styles that matter to compilers and linters. Doing the conversion by hand is slow and error-prone; letting the tool apply the rule consistently is fast and tidy.
The everyday cases
UPPERCASE turns every letter capital. It works well for short acronyms, labels, and the occasional bit of emphasis, but a whole paragraph in caps reads as shouting and is genuinely harder to scan, so use it sparingly.
lowercase strips every capital out. It is handy for normalizing data, cleaning up text that arrived in a jumble, or matching the relaxed lowercase aesthetic some brands favor. It is also the quickest fix for a sentence that got typed entirely in caps by accident.
Sentence case capitalizes only the first letter of each sentence and leaves the rest as written. This is the natural style for body copy, emails, and most modern user-interface text, because it reads the way people actually write.
Title Case capitalizes the major words and lowercases the small connecting ones. It is the traditional style for headings, book and article titles, song names, and headlines. Title case is where most people get tripped up, because the exact rules depend on which style guide you follow.
Title case is not one rule: AP vs Chicago
Both the Associated Press (AP) and the Chicago Manual of Style agree on the basics: capitalize the first and last word, plus all nouns, pronouns, verbs, adjectives, and adverbs. Both also lowercase short articles such as a, an, and the, the short conjunctions for, and, nor, but, and or, and short prepositions.
The disagreements are in the details. AP lowercases prepositions of three letters or fewer but capitalizes longer ones, and it capitalizes to when it is part of an infinitive. Chicago lowercases to in infinitives and lowercases prepositions regardless of length. The conjunctions yet and so are lowercased in AP but capitalized in Chicago. None of this is intuitive, which is exactly why a converter that knows the rules saves time and arguments.
Developer cases: naming variables the right way
Programmers need a different family of styles because identifiers cannot contain spaces. Each language community settles on its own convention, and mixing them looks sloppy or breaks linters.
- camelCase — first word lowercase, each later word capitalized, no spaces:
userName. Common in JavaScript, Java, and Kotlin variables. - PascalCase — like camelCase but the first word is capitalized too:
UserName. Used for class and type names in many languages. - snake_case — all lowercase with underscores between words:
user_name. The standard for Python, Ruby, and SQL. - kebab-case — all lowercase with hyphens:
user-name. Popular for URLs, CSS class names, and file names.
A converter that handles these lets you take a label like "User Name" and instantly get the right identifier for whichever language you are writing, then switch it again when you move the same idea into a database column or a CSS rule.
Quick, everyday uses
The two most common reasons people reach for this tool are unglamorous and constant: fixing text that got typed with Caps Lock on, and reformatting a heading or variable name without retyping it. Drop in a SHOUTING SENTENCE and pull out a tidy one. Paste a column header and get a clean snake_case field. Once it is in your workflow you will use it more than you expect. If you also need to measure what you are editing, pair it with the word counter, and browse the rest of our text tools for trimming, sorting, and cleaning up text.
Frequently asked questions
Is my text uploaded anywhere?
No. The conversion runs entirely in your browser using JavaScript, so the text you paste never gets sent to a server. You can even use it offline once the page has loaded.
What is the difference between Title Case and Sentence case?
Title Case capitalizes most words in a heading, while Sentence case capitalizes only the first letter of each sentence. Use Title Case for headlines and titles, and Sentence case for normal body text and emails.
Which title case style should I use, AP or Chicago?
It depends on your context. Journalists and many websites follow AP, while books and academic publishing often follow Chicago. If you have no house style, pick one and apply it consistently.
What is camelCase versus snake_case?
camelCase joins words with capital letters and no separators, like userName, and is common in JavaScript and Java. snake_case uses lowercase words separated by underscores, like user_name, and is standard in Python and SQL.
Can it fix text I accidentally typed in all caps?
Yes. Paste the all-caps text and choose lowercase or Sentence case. Sentence case is usually best because it restores normal capitalization at the start of each sentence.
Does converting case change the words themselves?
No. A case converter only changes which letters are uppercase or lowercase and, for developer styles, the separators between words. The actual words and their order stay the same.