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overview

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 ## Authentication
 
-For details on both authentication methods and when to use each, see [Authentication](https://platform.claude.com/docs/en/manage-claude/authentication). All requests to the Claude API must include these headers:
+For details on each authentication method and when to use it, see [Authentication](https://platform.claude.com/docs/en/manage-claude/authentication). Requests to the Claude API include these headers:
 
-| Header              | Value                                                                                                                                                                                                                       | Required                              |
-| ------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------- |
-| `x-api-key`         | Your API key from Console                                                                                                                                                                                                   | One of `x-api-key` or `Authorization` |
-| `Authorization`     | `Bearer <token>`, where `<token>` is a short-lived access token obtained from `POST /v1/oauth/token` through [Workload Identity Federation](https://platform.claude.com/docs/en/manage-claude/workload-identity-federation) | One of `x-api-key` or `Authorization` |
-| `anthropic-version` | API version (for example, `2023-06-01`)                                                                                                                                                                                     | Yes                                   |
-| `content-type`      | `application/json`                                                                                                                                                                                                          | Yes                                   |
+| Header                   | Value                                                                                                                                                                                                                                                                    | Required                                                                                                                                                             |
+| ------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `x-api-key`              | Your API key from Console                                                                                                                                                                                                                                                | One of `x-api-key` or `Authorization`                                                                                                                                |
+| `Authorization`          | `Bearer <token>`, where `<token>` is a short-lived access token obtained from `POST /v1/oauth/token` through [Workload Identity Federation](https://platform.claude.com/docs/en/manage-claude/workload-identity-federation)                                              | One of `x-api-key` or `Authorization`                                                                                                                                |
+| `anthropic-workspace-id` | ID of the [workspace](https://platform.claude.com/docs/en/manage-claude/workspaces) the request runs in (for example, `wrkspc_01JwQvzr7rXLA5AGx3HKfFUJ`). See [Select a workspace](https://platform.claude.com/docs/en/manage-claude/authentication#select-a-workspace). | Required with a multi-workspace API key. Optional for other API keys. Not used with Workload Identity Federation tokens, which select a workspace at token exchange. |
+| `anthropic-version`      | API version (for example, `2023-06-01`)                                                                                                                                                                                                                                  | Yes                                                                                                                                                                  |
+| `content-type`           | `application/json`                                                                                                                                                                                                                                                       | Yes                                                                                                                                                                  |
 
-If you are using the [Client SDKs](https://platform.claude.com/docs/en/api/overview#client-sdks), the SDK will send these headers automatically. For API versioning details, see [API versions](https://platform.claude.com/docs/en/api/versioning).
+If you are using the [Client SDKs](https://platform.claude.com/docs/en/api/overview#client-sdks), the SDK sends the authentication, version, and content-type headers automatically; you pass `anthropic-workspace-id` yourself when your key needs it. For API versioning details, see [API versions](https://platform.claude.com/docs/en/api/versioning).
 
 When accessing Claude through a [cloud platform](https://platform.claude.com/docs/en/api/overview#claude-api-vs-cloud-platforms), authentication is integrated with the cloud provider's IAM system. See the platform-specific documentation for supported credential types, required headers, and authentication options.
 
 ### Getting API keys
 
-The API is made available through the web [Console](https://platform.claude.com/). You can use [playground](https://platform.claude.com/playground) to try out the API in the browser and then generate API keys in [Account Settings](https://platform.claude.com/settings/keys). You choose each key's [expiration](https://platform.claude.com/docs/en/manage-claude/authentication#key-expiration) when you create it. Use [workspaces](https://platform.claude.com/settings/workspaces) to segment your API keys and [control spend](https://platform.claude.com/docs/en/api/rate-limits) by use case.
+The API is made available through the web [Console](https://platform.claude.com/). You can use [playground](https://platform.claude.com/playground) to try out the API in the browser and then generate API keys in [Account Settings](https://platform.claude.com/settings/keys). You choose each key's type (see [Key types](https://platform.claude.com/docs/en/manage-claude/authentication#key-types)) and its [expiration](https://platform.claude.com/docs/en/manage-claude/authentication#key-expiration) when you create it. Use [workspaces](https://platform.claude.com/settings/workspaces) to separate environments and [control spend](https://platform.claude.com/docs/en/api/rate-limits) by use case.
 
 ## Client SDKs