camelCase joins words together with no spaces or separators, capitalizing the first letter of every word except the first — like "userFirstName". It's the standard naming convention for variables and function names in JavaScript, Java, and many other languages. This converter breaks your input into words wherever it finds spaces, hyphens, underscores, digits, or an existing uppercase letter starting a new word (so "user_first-name" and "UserFirstName" both convert correctly), then rejoins them as camelCase.
Spaces, hyphens, underscores, digit runs, and transitions between lowercase and uppercase letters all split the input into separate words before they're rejoined in camelCase, so this works on snake_case, kebab-case, PascalCase, and plain sentences alike.
They're identical except for the very first letter: camelCase starts lowercase ("userName"), while PascalCase capitalizes every word including the first ("UserName"). PascalCase is typically used for class and type names.
Yes — runs of digits are treated as their own word, so "user2 name" becomes "user2Name" rather than merging the digits into the surrounding text.