JSON Key Case Conventions – camelCase vs snake_case
Published 2026-02-16 · convertcase.in
JSON does not enforce any naming convention, but different ecosystems have strong preferences. Here is what to use and when.
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1JavaScript APIs
JavaScript-native APIs typically use camelCase JSON keys: { "userId": 1, "firstName": "John" }2Python / Django APIs
Python APIs often use snake_case: { "user_id": 1, "first_name": "John" }3Converting
When bridging JS and Python systems, convert keys at the API boundary. Libraries: humps (JS), marshmallow (Python).
Frequently Asked Questions
Should JSON use camelCase or snake_case?
Google's JSON Style Guide recommends camelCase. But follow your backend language's convention for consistency.