> ## Documentation Index
> Fetch the complete documentation index at: https://sendmux.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# SDKs

> Choose a Sendmux SDK package and the API surface it should use.

Sendmux SDKs give your application package-managed clients for the Sending, Mailbox, and Management APIs.

Use an umbrella package when one application needs more than one API surface. Use a surface package when you want a smaller dependency for one job.

<Info>
  Create the credential in Sendmux before you install a package. Sending
  clients accept a send-capable `smx_mbx_` key or owner-approved Sending-resource `smx_agent_` token. Mailbox clients accept
  `smx_mbx_` keys or scoped `smx_agent_` tokens. Management clients use
  team-scoped `smx_root_` keys.
</Info>

## Choose a surface

| Surface    | Use it for                                                                                                     | API key                                                     |
| ---------- | -------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------- |
| Sending    | Send single or batch emails.                                                                                   | `smx_mbx_` or owner-approved `smx_agent_` with `email.send` |
| Mailbox    | Read, search, and organise mailbox data. Mailbox keys can also send from the mailbox.                          | `smx_mbx_` or scoped `smx_agent_`                           |
| Management | Manage team resources such as domains, sending accounts, mailboxes, webhooks, logs, metrics, and billing data. | `smx_root_`                                                 |

<Note>
  Pre-claim `smx_agent_` tokens are mailbox-compatible only. Owner-approved Sending-resource `smx_agent_` tokens can send. Pre-claim self-registered agent tokens include `mailbox.read` and `email.receive`, not `email.send`.
</Note>

## Choose a package family

| Language   | Umbrella package | Surface packages                                              |
| ---------- | ---------------- | ------------------------------------------------------------- |
| TypeScript | `@sendmux/sdk`   | `@sendmux/sending`, `@sendmux/mailbox`, `@sendmux/management` |
| Python     | `sendmux-sdk`    | `sendmux-sending`, `sendmux-mailbox`, `sendmux-management`    |
| Go         | `sendmux.ai/go`  | `sending`, `mailbox`, `management`, and `sdk` subpackages     |
| PHP        | `sendmux/sdk`    | `sendmux/sending`, `sendmux/mailbox`, `sendmux/management`    |
| Ruby       | `sendmux-sdk`    | `sendmux-sending`, `sendmux-mailbox`, `sendmux-management`    |

## Related developer tools

<CardGroup cols={2}>
  <Card title="CLI" icon="terminal" href="/docs/cli">
    Install the Sendmux CLI with Snap, Homebrew, or npm for terminal workflows.
  </Card>

  <Card title="MCP servers" icon="plug" href="/docs/guides/mcp">
    Connect AI tools to Sendmux docs and authorised product tools.
  </Card>
</CardGroup>

## Next steps

<CardGroup cols={2}>
  <Card title="Versioning and support" icon="rotate" href="/docs/sdks/versioning-support">
    Understand package releases, compatibility, and support details.
  </Card>

  <Card title="API keys" icon="key" href="/docs/guides/api-keys">
    Create scoped credentials before using an SDK.
  </Card>

  <Card title="Sending API" icon="paper-plane" href="/docs/sending-api/introduction">
    Review the Sending API contract used by sending SDK packages.
  </Card>

  <Card title="Management API" icon="chart-line" href="/docs/api/introduction">
    Review the Management API contract used by management SDK packages.
  </Card>

  <Card title="Mailbox API" icon="inbox" href="/docs/mailbox-api/introduction">
    Review the Mailbox API contract used by mailbox SDK packages.
  </Card>
</CardGroup>