Naming Conventions: camelCase, snake_case, kebab-case Explained

Programming has surprisingly many ways to write a multi-word name. Most communities have settled on conventions, and following them isn't pedantry — it's a courtesy that lets the next developer read your code without friction.

The casing zoo

camelCase — first word lowercase, subsequent words capitalized. userProfile
PascalCase — every word capitalized. UserProfile
snake_case — lowercase, words joined by underscores. user_profile
SCREAMING_SNAKE_CASE — uppercase snake_case. USER_PROFILE
kebab-case — lowercase, words joined by hyphens. user-profile
Train-Case — capitalized words joined by hyphens. User-Profile
dot.case — lowercase, words joined by dots. user.profile

Convert any name: Paste in one case, get every variation instantly.

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Conventions by language

Language	Variables	Functions	Classes/Types	Constants
JavaScript / TypeScript	camelCase	camelCase	PascalCase	SCREAMING_SNAKE
Python	snake_case	snake_case	PascalCase	SCREAMING_SNAKE
Java	camelCase	camelCase	PascalCase	SCREAMING_SNAKE
Go	camelCase / PascalCase*	camelCase / PascalCase*	PascalCase	PascalCase
Rust	snake_case	snake_case	PascalCase	SCREAMING_SNAKE
C#	camelCase	PascalCase	PascalCase	PascalCase
SQL	snake_case	—	—	—

* In Go, capitalization controls visibility: PascalCase is exported, camelCase is private to the package.

Conventions by context

URLs: kebab-case (/user-profile) — readable, no encoding needed.
CSS class names: kebab-case (.user-profile) — matches CSS naming tradition.
HTML attributes: kebab-case (data-user-id) — required by spec for custom data attributes.
HTTP headers: Train-Case (Content-Type) — case-insensitive but conventionally Train-Case.
Environment variables: SCREAMING_SNAKE (DATABASE_URL) — universal Unix convention.
JSON keys: usually camelCase (matches JavaScript) or snake_case (matches Python).
File names: kebab-case (user-profile.tsx) is most common in JS/TS; snake_case in Python/Ruby; PascalCase for class files in Java/C#.

JSON: the cross-cultural minefield

JSON traveled between every language ecosystem, so naming conventions vary. Common practices:

JavaScript/Node APIs: camelCase ({"firstName": "Ada"})
Python/Ruby APIs: snake_case ({"first_name": "Ada"})
Public APIs serving multiple languages: often snake_case for clarity

When consuming third-party APIs, accept their convention; don't force your local style. Use mapping libraries (Jackson, Gson, attrs) to translate between JSON keys and your in-language field names.

Practical tips

Follow the convention of the existing codebase over personal preference.
Use auto-formatters (Prettier, Black, gofmt) — they don't change names but enforce a clean baseline.
Use linters like ESLint and pylint to catch convention violations.
Don't rename across the codebase just because you prefer a different convention. Pick your battles.