# Tech Hub

Technical documentation for developers building on or integrating with Fira Protocol — a modular fixed-rate and variable-rate lending infrastructure on Ethereum.

## Start Here

{% content-ref url="fira-protocol-primer" %}
[fira-protocol-primer](https://docs.fira.money/developers/fira-protocol-primer)
{% endcontent-ref %}

## Explore

<table data-card-size="large" data-view="cards"><thead><tr><th></th><th></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><strong>Features</strong></td><td>Fixed-rate lending, variable-rate lending, BT/CT/FW tokens, AMM, rehypothecation, and liquidity injection</td><td><a href="features">features</a></td></tr><tr><td><strong>Architecture</strong></td><td>System layers, module dependencies, reentrancy, access control, and upgradability</td><td><a href="architecture">architecture</a></td></tr><tr><td><strong>Smart Contracts</strong></td><td>Protocol contracts, token contracts, utility contracts, oracles, and math libraries</td><td><a href="protocol-contracts">protocol-contracts</a></td></tr><tr><td><strong>User Flows</strong></td><td>Step-by-step transaction flows for borrowing, lending, LPing, and trading</td><td><a href="user-flows">user-flows</a></td></tr><tr><td><strong>Deployment</strong></td><td>All mainnet addresses, market IDs, oracle pipelines, router facets, and key roles</td><td><a href="deployment">deployment</a></td></tr><tr><td><strong>Events &#x26; Indexing</strong></td><td>On-chain event reference and position measurement methodology</td><td><a href="events-and-indexing">events-and-indexing</a></td></tr><tr><td><strong>Integrations</strong></td><td>Interfaces and integration patterns for building on Fira</td><td><a href="integrations">integrations</a></td></tr><tr><td><strong>Security &#x26; Audits</strong></td><td>Security design principles, six independent audits, and bug bounty</td><td><a href="security-and-audits">security-and-audits</a></td></tr></tbody></table>

## Quick Reference

| Resource                  | Link                                                                                         |
| ------------------------- | -------------------------------------------------------------------------------------------- |
| **Mainnet Contracts**     | [Deployment](https://docs.fira.money/developers/deployment)                                  |
| **Source Code**           | [github.com/usual-dao/fira](https://github.com/usual-dao/fira)                               |
| **Lending Market Source** | [github.com/usual-dao/fira-lending-market](https://github.com/usual-dao/fira-lending-market) |
| **Bug Bounty**            | [Sherlock Program](https://docs.fira.money/security-and-risk/bug-bounty)                     |
| **Glossary**              | [Developer Glossary](https://docs.fira.money/developers/glossary)                            |
| **Whitepaper**            | [Fira Whitepaper](https://docs.fira.money/resources/whitepaper)                              |

## Key Facts

| Parameter                | Value                                        |
| ------------------------ | -------------------------------------------- |
| Chain                    | Ethereum Mainnet                             |
| Router                   | `0xFF615E63aAF2d1B1EE4AdFD34a5840747185d8A0` |
| FW-USDC                  | `0x62F5366C9E21A95326C461a098a408e034e017b3` |
| BT Expiry (V1)           | May 7, 2026 · May 27, 2026 (USDG)            |
| Fixed-Rate Collateral    | PT-USDe, PT-sUSDe, PT-USDG                   |
| Variable-Rate Collateral | wstETH, cbBTC                                |
| Audits                   | 6 independent external + internal review     |


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