snake_case Converter

Turn any phrase into snake_case — free, instant, runs in your browser.

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What is snake_case?

snake_case writes every word in lowercase and joins them with underscores. The name comes from the snake-like shape of the underscores running along the baseline of the text.

snake_case examples

hello world example → hello_world_example
UserFirstName → user_first_name
max retry count → max_retry_count

Where is snake_case used?

snake_case is the convention for variables and functions in Python (recommended by PEP 8), Ruby and Rust, and it is the dominant style for SQL table and column names. It is also popular for file names and for JSON keys in APIs that value readability.

snake_case and its relatives

Replacing the underscores with hyphens gives kebab-case; uppercasing everything gives CONSTANT_CASE, also called SCREAMING_SNAKE_CASE. This converter understands all of these styles as input, so pasting camelCase or kebab-case text converts cleanly.

Common mistakes when converting case

Expecting editorial Title Case. The Title Case button capitalizes every word, including short ones: "the lord of the rings" becomes "The Lord Of The Rings". Style guides like AP and Chicago keep words such as "of", "the" and "and" lowercase, so adjust those by hand afterward.
Losing apostrophes. Word-based styles (Title Case, camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE) split on anything that is not a letter or digit, so "don't stop" turns into "Don T Stop" or "don_t_stop". Remove or restore apostrophes after converting.
Sentence case and proper nouns. Sentence case lowercases the whole text, then capitalizes only the first letter of each sentence, so "i visited NASA in june. it was fun." becomes "I visited nasa in june. It was fun." Re-capitalize names and acronyms yourself.

Pro tips

Rescue a Caps Lock accident with InVeRsE CaSe. Text typed as "hELLO wORLD" while Caps Lock inverted your Shift key flips back to "Hello World" in one click.
Acronyms split cleanly. "HTMLParser" converts to "htmlParser" with camelCase and "html_parser" with snake_case, because the word splitter detects where an acronym ends and the next word begins.
Only letters alternate. In aLtErNaTiNg CaSe, digits, spaces and punctuation stay in place and do not break the pattern: "abc 123 def" becomes "aBc 123 dEf".

Frequently asked questions

What is the difference between snake_case and kebab-case?

snake_case joins lowercase words with underscores (user_name), kebab-case with hyphens (user-name). snake_case is the norm in Python, Ruby and SQL; kebab-case dominates URLs, CSS classes and HTML attributes.

What is SCREAMING_SNAKE_CASE?

It is snake_case written in all capitals — the same style this site calls CONSTANT_CASE, used for constants and environment variables like MAX_RETRY_COUNT. See the CONSTANT_CASE converter linked below.

Does the converter understand camelCase input?

Yes. Word boundaries are detected automatically, so pasting 'userFirstName' or 'user-first-name' converts to 'user_first_name' without any manual cleanup.

Other case converters

Or switch between every style in one place on the Case Converter homepage.