camelCase vs snake_case: A Guide to Naming Conventions in Code

Spaces aren't allowed in identifiers, so programmers invented a dozen ways to glue words together. Using the wrong one isn't a bug, but it marks code as out of place — every language and ecosystem has its conventions.

The main cases

camelCase — first word lower, rest capitalized (userName). PascalCase — every word capitalized (UserName). snake_case — lowercase with underscores (user_name). kebab-case — lowercase with hyphens (user-name). CONSTANT_CASE — uppercase with underscores (USER_NAME). Convert a phrase into all of them at once with the code case converter.

Who uses what

JavaScript/Java: camelCase for variables, PascalCase for classes. Python/Ruby: snake_case for variables and functions, PascalCase for classes. CSS and URLs: kebab-case. Constants: CONSTANT_CASE almost everywhere. Databases: usually snake_case columns.

Why consistency matters

Mixed casing makes code harder to scan and breaks autocomplete habits. The rule isn't "this case is best" — it's "match the surrounding code and the language's convention". A Python file full of camelCase reads as foreign even though it runs fine.

Bonus: URL slugs

For web addresses and filenames, kebab-case wins — it's readable and search-engines treat hyphens as word separators. Turn any title into a clean URL slug with the slug generator.

Let tools do the conversion

Renaming a variable across cases by hand is error-prone. Paste the phrase into the code case converter and copy the exact form you need — camelCase for the variable, CONSTANT_CASE for the config key, kebab-case for the CSS class.