# Yearn

> Yearn is a decentralized finance (DeFi) yield aggregator that automatically maximizes yields on deposited assets through battle-tested on-chain strategies. Yearn operates vaults on Ethereum, Katana, Base, Arbitrum, Optimism, and Polygon. Kong REST is the canonical source for live vault data.

## Overview

Yearn vaults accept ERC-20 token deposits and automatically route funds to the highest-yielding strategies, compounding returns over time. The protocol is non-custodial and permissionless — deposits are held entirely in smart contracts.

## Main Pages

- [Home](https://yearn.fi/): Landing page and product overview
- [Vaults](https://yearn.fi/vaults): Browse all available yield vaults across supported chains
- [Portfolio](https://yearn.fi/portfolio): View deposited assets and accumulated earnings

## Primary Machine-Readable Vault Data

- [Canonical Active Vault List (JSON)](https://kong.yearn.fi/api/rest/list/vaults): Source of truth for current vault metadata, visibility, APY, TVL, and vault addresses
- `https://kong.yearn.fi/api/rest/snapshot/{chainId}/{address}`: Canonical vault detail snapshot; replace `chainId` with the numeric chain ID and `address` with the vault contract address
- `https://yearn.fi/vaults/{chainId}/{address}`: Public vault page URL; maps to the Kong snapshot endpoint above for live vault detail data
- [Sitemap](https://yearn.fi/sitemap.xml): XML sitemap listing canonical public vault page URLs

## Derived Convenience Markdown

These markdown endpoints are generated live from Kong REST for agent and crawler convenience. Treat Kong JSON as the source of truth, especially for financial values.

- [All Active Vaults (Markdown)](https://yearn.fi/api/vaults/markdown): Kong-derived summary of public active Yearn Single Asset and LP Token vaults
- [All Active Vaults Filtered by Chain](https://yearn.fi/api/vaults/markdown?chainId=1): Pass a numeric `chainId` to filter by chain
- [Example Single Vault (Markdown)](https://yearn.fi/api/vault/markdown?chainId=1&address=0xBe53A109B494E5c9f97b9Cd39Fe969BE68BF6204): Kong-derived detail summary; replace `chainId` and `address`

## Vault Data Semantics

- Public active vaults exclude non-Yearn entries, entries where `inclusion.isYearn` is false, hidden vaults, retired vaults, legacy vaults, and underlying single-strategy entries.
- `/api/vaults/markdown` does not apply a TVL minimum.
- Use numeric `chainId` values in URLs and API requests.
- Treat the vault contract address as the vault identifier, and pair it with `chainId` for cross-chain API calls and page URLs.
- APY, APR, TVL, strategy composition, and availability are time-sensitive live data. Refresh from Kong at retrieval time.
- Generated markdown is a thin interpretation layer, not a historical archive or independent data source.

## External Resources

- [Yearn Docs](https://docs.yearn.fi): Technical documentation, strategy explanations, and developer guides
- [GitHub](https://github.com/yearn): Open-source smart contracts and tooling
- [Blog](https://blog.yearn.fi): Protocol updates and announcements
- [Governance Forum](https://gov.yearn.fi): On-chain governance proposals and discussion
- [Kong API (JSON)](https://kong.yearn.fi/api/rest/list/vaults): Raw JSON vault list from Yearn's data API

## Supported Chains

| Chain | Chain ID |
|-------|----------|
| Ethereum | 1 |
| Optimism | 10 |
| Polygon | 137 |
| Fantom | 250 |
| Base | 8453 |
| Arbitrum | 42161 |
| Sonic | 146 |
| Katana | 747474 |