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

# Introduction

> On/off-ramps and swaps: buy and sell stablecoins and yield-bearing stablebonds with fiat, or swap one asset for another.

<Note>
  **v2 is in beta.** Endpoints and request and response shapes can still change. We announce every change in the [changelog](/changelog) before it ships. The [v1 docs](/introduction) stay available from the version menu.
</Note>

<Info>
  **Build against the sandbox first.** Every example in these docs works against `https://api.sand.etherfuse.com` with no real money or personal data. Start with the [Quickstart](/v2/quickstart).
</Info>

## Get started

<CardGroup cols={2}>
  <Card title="Quickstart" icon="rocket" href="/v2/quickstart">
    Register payment accounts, quote, create an order and fund it in sandbox.
  </Card>

  <Card title="Initial setup" icon="flask" href="/v2/initial-setup">
    Create a sandbox account, generate API keys, and learn the base URLs.
  </Card>

  <Card title="Onboard a customer" icon="user-check" href="/v2/guides/kyc-websdk">
    Run KYC with a single hosted launch (`/idv`).
  </Card>

  <Card title="API Reference" icon="code" href="/v2/api-reference/payment-accounts/register-payment-account">
    Browse all endpoints with live "Try it" requests and code samples.
  </Card>
</CardGroup>

## What you can build

<CardGroup cols={2}>
  <Card title="Onramp" icon="arrow-up-right-dots" href="/v2/guides/testing-onramps">
    Customer pays fiat from a bank account, receives tokens in a wallet.
  </Card>

  <Card title="Offramp" icon="arrow-down" href="/v2/guides/testing-offramps">
    Customer sends tokens from a wallet, receives fiat in a bank account.
  </Card>

  <Card title="Swap" icon="right-left" href="/v2/guides/testing-swaps">
    Customer exchanges one token for another on the same chain.
  </Card>

  <Card title="Cross-chain transfer" icon="link" href="/v2/overview">
    Customer sends a token from a wallet on one supported chain to a wallet on another.
  </Card>
</CardGroup>

## Core concepts & reference

<CardGroup cols={2}>
  <Card title="How it works" icon="diagram-project" href="/v2/overview">
    Payment accounts, rails, quotes, orders and their statuses.
  </Card>

  <Card title="Authentication" icon="key" href="/v2/authentication">
    API-key auth, sandbox vs. production keys, and the one header gotcha.
  </Card>

  <Card title="Errors" icon="circle-exclamation" href="/v2/errors">
    Every problem type the API returns, with causes and fixes.
  </Card>

  <Card title="Pagination" icon="layer-group" href="/v2/pagination">
    How to page through payment accounts, orders and subscriptions.
  </Card>

  <Card title="Idempotency" icon="rotate" href="/v2/idempotency">
    Retry order creation with the same `quoteId` and get one order.
  </Card>

  <Card title="Webhooks" icon="bell" href="/v2/webhooks">
    Signed event delivery for orders, payment accounts and KYC.
  </Card>

  <Card title="SDKs" icon="cube" href="/v2/sdks">
    TypeScript and Rust libraries for the on-chain Stablebond side.
  </Card>
</CardGroup>

## Build with AI & tools

<CardGroup cols={3}>
  <Card title="MCP Server" icon="robot" href="/v2/mcp-overview">
    Connect Claude, ChatGPT, or any MCP client and drive the Etherfuse API in natural language.
  </Card>

  <Card title="llms.txt" icon="file-lines" href="https://docs.etherfuse.com/llms.txt">
    A machine-readable index of these docs for LLMs and AI assistants.
  </Card>

  <Card title="OpenAPI spec" icon="file-code" href="https://docs.etherfuse.com/openapi-v2.json">
    Download `openapi-v2.json` to import into Postman, Insomnia, or generate a client.
  </Card>
</CardGroup>


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