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

# Introduction

> Welcome to Barker Yield Engine — embed institutional-grade stablecoin yield in your wallet or payment app.

## What is Barker Yield Engine?

Barker Yield Engine lets you offer your users **non-custodial USDC yield** through a per-partner `BarkerEngine` smart contract. You earn a configurable share of yield via on-chain fee split — no subscription fees, no usage billing, all settlement happens on-chain in real time.

## Two ways to integrate

You pick one of two integration modes. Both run against the same engines, the same APIs, the same on-chain fee split — they only differ in **where the deposit/withdraw UI lives**.

<CardGroup cols={2}>
  <Card title="Embed (iframe)" href="/embed" icon="window">
    Drop a single line of HTML into your app. We render the deposit/withdraw UI, handle wallet connection, gas, transaction confirmations, APY display.

    **Best when** you want the fastest possible launch and don't need to control every pixel.
  </Card>

  <Card title="Headless API" href="/integration-api" icon="code">
    Build your own deposit/withdraw UI on top of our REST API. Your frontend talks to your users' wallets directly and calls the engine contract with standard ERC-4626 functions. We provide data, metrics, and read-only helpers.

    **Best when** flow must be inline (KYC → deposit → confirmation), or UI must stay fully on your domain.
  </Card>
</CardGroup>

Not sure which one fits? See [Choosing an integration mode](/integration-modes).

## How it works

1. We deploy a dedicated `BarkerEngine` contract for your account on the chain you choose (Base / Arbitrum / Ethereum / BNB).
2. Your users deposit USDC into the engine — through the embed iframe **or** through your own UI calling the engine directly.
3. The engine deposits to a curated underlying ERC-4626 vault selected for that chain.
4. Yield is generated. Each `accrueFee()` call splits yield as `barkerFeeBps + partnerFeeBps`, minting engine shares to both `barkerFeeRecipient` and your `partnerFeeRecipient`.
5. You can `redeem()` your accumulated shares anytime, or leave them compounding.

**Key properties:**

* 100% non-custodial: user funds always traceable on chain
* Per-partner engine: AUM and fees independently verifiable
* No SaaS billing: revenue model is `partnerFeeBps` percentage of yield
* Multi-chain: same API surface across all supported chains
* Multi-tier ready: offer 3 risk profiles (conservative / balanced / aggressive) by registering 3 product slugs — see [Multi-tier products](/multi-tier-products)

## Next steps

* [Choosing an integration mode](/integration-modes) — decision tree, 2 minutes
* [Quickstart](/quickstart) — first API call in 5 minutes
* [Embed](/embed) — iframe path
* [Headless API](/integration-api) — end-to-end pure-API path
* [Compliance & risk](/compliance) — custody, KYC, disclosures