# Recommended Deployment Shape Unlike `CityClient` (which runs in the browser against a user's wallet), `CityCardClient` should run **server-side**. API keys used to authenticate with card providers are secret credentials and must never be exposed to the frontend. PAN reveal and card control operations are sensitive, and card state should be correlated with your internal user records and compliance pipeline before any action is taken. A typical deployment places `CityCardClient` behind your own authenticated API layer, where you can enforce authorization, rate-limiting, and audit logging before forwarding calls to the provider. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://city-protocol.gitbook.io/docs/software-development-kit/card/recommended-deployment-shape.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.