# Teller Protocol (Teller Finance)

> Teller Protocol is a decentralized, multi-chain lending and borrowing
> protocol (Ethereum, Base, Arbitrum, Polygon, BNB), offering fixed-APR,
> time-based loans from isolated lending pools with no oracle-driven margin
> calls. Integration is via on-chain smart contracts, a GraphQL subgraph, and
> an embeddable Cash Advance widget — not a hosted REST API.

## Overview
- Type: DeFi lending/borrowing protocol (on-chain smart contracts)
- Website (current): https://www.teller.org/
- Website (legacy brand): https://www.teller.finance/
- Documentation: https://docs.teller.org/
- Cash Advance Widget: https://www.teller.org/widget
- GitHub organization: https://github.com/teller-protocol
- Blog: https://medium.com/teller-finance

## Developer surface
- Smart contracts (Solidity): https://github.com/teller-protocol/teller-protocol-v2 (and teller-protocol-v1)
- GraphQL subgraph (The Graph): https://github.com/teller-protocol/subgraph
- Embeddable widget (npm, official): @teller-protocol/teller-widget — https://github.com/teller-protocol/teller-widget
- Risk profile algorithms: https://github.com/teller-protocol/Risk-Profile-Algorithms

## Integration notes
- The primary programmatic interface is the TellerV2 smart contract, through
  which pool owners open markets and lenders/borrowers participate.
- Read-side data (markets, loans, bids, commitments) is served over GraphQL by
  the Teller subgraph, which indexes protocol events.
- Front-end integration is available via the Teller Widget, a drop-in React
  component published to npm.

## What this is NOT
- There is no hosted REST/OpenAPI, no OAuth 2.0 authorization server, and no
  API-key program. Authentication is wallet-based (on-chain transactions).