Text Case Converter

The hard part is not casing — it is finding the words

Any tool can uppercase a string. The reason most case converters produce garbage is that they split on spaces and underscores only, so parseHTTPResponse becomes parse_h_t_t_p_response. Getting this right means detecting boundaries that are not written down:

• Explicit separators — spaces, underscores, hyphens, dots, slashes.
• Camel humps — a lowercase letter followed by an uppercase one, as in userId.
• Acronym boundaries — HTTPResponse splits into HTTP and Response, because a run of capitals followed by a capital plus lowercase marks the end of the acronym.

This tool applies all three rules before re-casing, so round-tripping between conventions does not progressively destroy your identifiers.

Worked example

Input	camelCase	snake_case	kebab-case
user_id	userId	user_id	user-id
parseHTTPResponse	parseHttpResponse	parse_http_response	parse-http-response
User ID	userId	user_id	user-id
XMLHttpRequest	xmlHttpRequest	xml_http_request	xml-http-request
2 fast 2 furious	fastFurious	fast_furious	fast-furious

Note the last row: leading digits are dropped, because an identifier cannot start with a digit in most languages. Numbers in the middle of a word are preserved.

Which convention, where

Language	Variables / functions	Types / classes	Constants
JavaScript, Java, TypeScript, C#	camelCase	PascalCase	CONSTANT_CASE
Python, Ruby	snake_case	PascalCase	CONSTANT_CASE
Go, Rust	camelCase / snake_case	PascalCase	CONSTANT_CASE
CSS, HTML, URLs, file names	kebab-case — lowercase and hyphenated, because host names and many file systems are case-insensitive
SQL	snake_case	Unquoted identifiers fold to upper case in most engines, so consistency matters more than the choice

Frequently asked questions

Why did my acronym get split into separate letters?

The input did not mark the boundary. parseHTTPResponse is handled correctly, but PARSEHTTPRESPONSE has no humps or separators to work from and is read as one word.

Can I convert a whole source file?

Yes, paste as much text as you like. Be aware that casing is applied to everything, including string literals and comments, so review the result before committing it.

What is the difference between Title Case and Sentence case?

Title Case capitalises every word. Sentence case capitalises only the first word of each sentence, which is what most prose and UI copy should use.

Does it handle non-Latin alphabets?

Casing follows Unicode rules where the browser supports them. Word splitting relies on Latin letters and digits, so scripts without spaces such as Chinese or Japanese are treated as a single word.