All Circle APIs use API keys as the mechanism to authenticate client requests.

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Keep Your API Keys Safe

Your API keys allow access to privileged operations on Circle APIs, so you must keep them secure at all times. Ensure your API key is always stored securely and never share it or record it in a medium that might be publicly accessible such as client-side code, public repositories, etc.

API Keys on Sandbox Environment

The Circle APIs are available on a sandbox environment which is ideal for quickly familiarizing yourself with the request & response formats and building prototypes, and writing your integration code.

If you don't yet have an API key on the sandbox environment, you can easily generate one by creating an account - it only takes a few seconds.

API Keys on Production Environment

To obtain production API keys, you need to apply for Circle Account and subsequently reach out to sales. We'll be happy to walk you through to the next steps.