> ## Documentation Index
> Fetch the complete documentation index at: https://base-a060aa97-docs-use-case-ia-overhaul.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# SDKs & APIs

> Every SDK and API for building on Base in one place — the Base Account SDK for wallet, auth, and payments, and the Base Chain API for JSON-RPC, Flashblocks, and tracing.

Two surfaces cover everything you build on Base: a client **SDK** for accounts, sign-in, and payments, and the **chain API** for reading and writing onchain. Pick the one that matches what you're calling.

<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 Chain API" icon="server" href="/base-chain/api-reference/rpc-overview">
    JSON-RPC, Flashblocks streaming, and Debug tracing against Base nodes.
  </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)                                       |
| 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 — issue stablecoins, facilitate payments, run private transactions — start with Build on Base.
</Card>