camelCase for many variables and JSON fields
The first word starts lowercase and later words start uppercase, with no separator.
PascalCase for many type names
Every word starts uppercase. It is common for classes, components, and exported types.
snake_case for databases and some languages
Lowercase words use underscores; CONSTANT_CASE uses the same separators in uppercase.
kebab-case for readable URLs
Hyphens remain visually clear and are common in slugs and CSS class names, while path case uses slashes to express hierarchy.
Word splitting is the irreversible step
The converter recognizes common whitespace, punctuation, camelCase, PascalCase, and acronym-to-word boundaries before rebuilding an identifier. That cannot recover an original boundary once a source such as userid has already merged two words. Review technical abbreviations and numbers, and keep the source beside the result until tests pass. Converting back from snake_case to camelCase may produce a useful equivalent, but it is not proof that the original identifier has been reconstructed exactly.
Treat names as contracts
A database column, JSON field, environment variable, CSS selector, import path, and public URL can be consumed by other systems. A capitalization change can therefore be breaking even when it looks cosmetic. Check language and platform conventions, case-sensitive filesystems, routing rules, generated clients, and existing consumers before a bulk rename. Use the downloadable output as a review list, not an automatic migration, and test collisions where two different source names normalize to the same lowercased identifier.