Convert camelCase to snake_case – Free Tool & Code
Published 2026-01-24 · convertcase.in
camelCase to snake_case is a common conversion needed when switching between JavaScript (camelCase) and Python (snake_case) codebases or APIs.
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1camelCase vs snake_case
camelCase: getUserProfile snake_case: get_user_profile
2In JavaScript
str.replace(/([A-Z])/g, "_$1").toLowerCase() // "getUserProfile" → "get_user_profile"
3In Python
import re re.sub(r'(?<!^)(?=[A-Z])', '_', str).lower()
4Online Tool
Use convertcase.in to paste camelCase text and convert to snake_case without writing any code.
Frequently Asked Questions
Why convert camelCase to snake_case?
Often needed when: a JS frontend sends camelCase to a Python backend that expects snake_case, or when migrating between codebases.