How to Convert Text Case Online — UPPERCASE, lowercase, camelCase, snake_case

The cases explained in one table

Name	Example	Where you see it
UPPERCASE	HELLO WORLD	Headlines, acronyms, environment variables
lowercase	hello world	Tags, URLs, most file paths
Title Case	Hello World	Book titles, page titles, headings
Sentence case	Hello world	UI copy, body text
camelCase	helloWorld	JavaScript, Java, C# variable names
PascalCase	HelloWorld	Class names, React components, C# types
snake_case	hello_world	Python, Ruby, SQL column names
kebab-case	hello-world	CSS classes, URLs, HTML attributes
CONSTANT_CASE	HELLO_WORLD	Config constants, env vars

Title Case is harder than it looks

"Capitalize every word" is wrong. English style guides (AP, Chicago, MLA) agree that short prepositions (of, in, for, on, at), articles (a, an, the), and conjunctions (and, but, or, nor) stay lowercase unless they're the first or last word. The case converter implements AP-style Title Case by default — you'll see it produce "The Lord of the Rings" rather than "The Lord Of The Rings".

Converting between naming conventions in code

The hardest part is going between word-separated ones (snake_case, kebab-case) and concatenated ones (camelCase, PascalCase). The converter handles this cleanly: it tokenizes the input by any separator or case boundary, then re-emits in the target style. my_variable_name → myVariableName → MyVariableName round-trips without data loss.

Slug generation

For URL slugs specifically, you also need to strip non-ASCII characters, collapse multiple spaces, and remove special punctuation. The text-to-slug tool adds these steps: "Tomorrow's 15% Sale!" → tomorrows-15-sale.

Locale quirks

Case conversion isn't always reversible across languages. Turkish has two i's (dotted and dotless) that uppercase differently. German's ß has historically had no uppercase form (though ẞ now exists). The converter uses the JavaScript Intl.toLocaleUpperCase / toLocaleLowerCase for English by default — for other locales, specify one explicitly.

Related text tools

Need to remove duplicate lines after case-normalizing? Remove duplicate lines. Need to count words in the output? Word counter. Reversing the string entirely? Text reverser.