camelCase vs snake_case vs kebab-case: Which to Use

camelCase joins words with no spaces, capitalizing each new word except the first (e.g., myVariableName). It is the dominant naming convention in JavaScript, Java, TypeScript, Swift, and most object-oriented languages for variables, functions, and method names.

JavaScript: const firstName = "Alice";

Java: String firstName = "Alice";

There is an important distinction between lowerCamelCase and UpperCamelCase (PascalCase). PascalCase capitalizes the first letter too (e.g., UserProfile). PascalCase is used for class names, constructors, React components, and TypeScript interfaces.

snake_case joins words with underscores, all lowercase (e.g., my_variable_name). It is the standard naming convention in Python, Ruby, PHP variables, and SQL column names.

Python: first_name = "Alice"

SQL: SELECT first_name FROM users

There is also SCREAMING_SNAKE_CASE, which uses all uppercase letters with underscores. It is the universal convention for constants across nearly all programming languages: MAX_RETRIES = 3

kebab-case joins words with hyphens, all lowercase (e.g., my-variable-name). It is used in CSS properties, HTML attributes, URL slugs, and file names.

CSS: background-color: #fff;

URL: https://example.com/my-blog-post

kebab-case cannot be used for variable names in most programming languages because hyphens are interpreted as the subtraction operator. Writing my-variable would be parsed as my minus variable, causing a syntax error. This is why kebab-case is restricted to contexts like CSS, URLs, and file naming.

The answer depends on the language or context. Here is a quick reference for the most common scenarios:

Switching between naming conventions is common when working across languages or APIs. A JavaScript frontend using camelCase often consumes a Python API that returns snake_case keys. Similarly, CSS class names in kebab-case need to be referenced as camelCase strings in JavaScript style objects.

Serialization libraries (like humps for JS or pydantic alias generators in Python) can automate these conversions. For quick one-off transforms, you can use our free converter:

Convert your text instantly with our free Snake/Kebab Case Converter →