> ## 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](https://docs.etherfuse.com/changelog.md) before it ships. The [v1 docs](https://docs.etherfuse.com/introduction.md) stay available from the version menu.

> [!NOTE]
>
> **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 getting API responses in **seconds** with the [Quickstart](https://docs.etherfuse.com/v2/quickstart.md).

## Get started

> [card] [Quickstart](https://docs.etherfuse.com/v2/quickstart.md)
>
> Register payment accounts, quote, create an order and fund it in sandbox.

> [card] [Initial setup](https://docs.etherfuse.com/v2/initial-setup.md)
>
> Create a sandbox account, generate API keys, and learn the base URLs.

> [card] [Onboard a customer](https://docs.etherfuse.com/v2/guides/kyc-websdk.md)
>
> Run KYC with a single hosted launch (`/idv`).

> [card] [API Reference](https://docs.etherfuse.com/v2/api-reference/payment-accounts/register-payment-account.md)
>
> Browse all endpoints with live "Try it" requests and code samples.

## What you can build

> [card] [Onramp](https://docs.etherfuse.com/v2/guides/testing-onramps.md)
>
> Customer pays fiat from a bank account, receives tokens in a wallet.

> [card] [Offramp](https://docs.etherfuse.com/v2/guides/testing-offramps.md)
>
> Customer sends tokens from a wallet, receives fiat in a bank account.

> [card] [Swap](https://docs.etherfuse.com/v2/guides/testing-swaps.md)
>
> Customer exchanges one token for another on the same chain.

> [card] [Cross-chain transfer](https://docs.etherfuse.com/v2/overview.md)
>
> Customer sends a token from a wallet on one supported chain to a wallet on another.

## Core concepts & reference

> [card] [How it works](https://docs.etherfuse.com/v2/overview.md)
>
> Payment accounts, rails, quotes, orders and their statuses.

> [card] [Authentication](https://docs.etherfuse.com/v2/authentication.md)
>
> API-key auth, sandbox vs. production keys, and the one header gotcha.

> [card] [Errors](https://docs.etherfuse.com/v2/errors.md)
>
> Every problem type the API returns, with causes and fixes.

> [card] [Pagination](https://docs.etherfuse.com/v2/pagination.md)
>
> How to page through payment accounts, orders and subscriptions.

> [card] [Idempotency](https://docs.etherfuse.com/v2/idempotency.md)
>
> Retry order creation with the same `quoteId` and get one order.

> [card] [Webhooks](https://docs.etherfuse.com/v2/webhooks.md)
>
> Signed event delivery for orders, payment accounts and KYC.

> [card] [SDKs](https://docs.etherfuse.com/v2/sdks.md)
>
> TypeScript and Rust libraries for the on-chain Stablebond side.

## Build with AI & tools

> [card] [MCP Server](https://docs.etherfuse.com/v2/mcp-overview.md)
>
> Connect Claude, ChatGPT, or any MCP client and drive the Etherfuse API in natural language.

> [card] [llms.txt](https://docs.etherfuse.com/llms.txt)
>
> A machine-readable index of these docs for LLMs and AI assistants.

> [card] [OpenAPI spec](https://docs.etherfuse.com/openapi-v2.json)
>
> Download `openapi-v2.json` to import into Postman, Insomnia, or generate a client.


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