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

# SDKs & APIs

> SDKs and APIs for accounts, identity verification, attribution, AI assistants, and direct Base chain access.

Choose the SDK or API surface that matches what your application needs to call. Base provides account and payment SDKs, identity verification APIs, transaction attribution guides, an MCP server for AI assistants, and direct chain APIs.

<CardGroup cols={2}>
  <Card title="Base Account SDK" icon="wallet" href="/sdks/base-account/overview">
    Universal sign-in and one-tap USDC payments. `pay`, `signInWithBase`, spend permissions, and the full TypeScript reference.
  </Card>

  <Card title="Base MCP" icon="robot" href="/agents/overview">
    Connect any AI assistant to a Base Account. Check balances, send funds, swap tokens, sign messages, and pay with x402.
  </Card>

  <Card title="Base Chain API" icon="server" href="/base-chain/api-reference/rpc-overview">
    JSON-RPC, Flashblocks streaming, and Debug tracing against Base nodes.
  </Card>

  <Card title="Builder Codes" icon="code" href="/base-chain/specs/reference/builder-codes/overview">
    Attribute onchain transactions to your app, wallet, or agent with ERC-8021.
  </Card>

  <Card title="Base Verify API" icon="user-check" href="/sdks/base-verify/overview">
    Prove verified account ownership and enforce Sybil-resistant eligibility policies.
  </Card>
</CardGroup>

## Install

<CodeGroup>
  ```bash npm theme={null}
  npm install @base-org/account
  ```

  ```bash pnpm theme={null}
  pnpm add @base-org/account
  ```

  ```bash yarn theme={null}
  yarn add @base-org/account
  ```
</CodeGroup>

## Which Surface Do I Need?

| You want to…                                           | Use                                                                                   |
| ------------------------------------------------------ | ------------------------------------------------------------------------------------- |
| Sign a user in or accept a USDC payment                | [Base Account SDK](/sdks/base-account/overview)                                       |
| Attribute transactions to an app, wallet, or agent     | [Builder Codes](/base-chain/specs/reference/builder-codes/overview)                   |
| Verify account ownership or enforce an identity policy | [Base Verify API](/sdks/base-verify/overview)                                         |
| Give an AI assistant a wallet it can transact with     | [Base MCP](/agents/overview)                                                          |
| Read balances, blocks, logs, or send raw transactions  | [Ethereum JSON-RPC](/base-chain/api-reference/rpc-overview)                           |
| Stream sub-second confirmations                        | [Flashblocks API](/base-chain/api-reference/flashblocks-api/flashblocks-api-overview) |
| Trace a transaction or block                           | [Debug API](/base-chain/api-reference/debug-api/debug_traceTransaction)               |

<Card title="Build a Use Case Instead" icon="rocket" href="/build-on-base/overview">
  If you'd rather start from an outcome — integrate DeFi, tokenize assets, issue stablecoins, or accept payments — start with Build on Base.
</Card>