# Builder Layer

**T-Rex provides an open toolkit for integration:**

* The **Passport SDK** lets developers add DID login and identity management to their applications, so users can authenticate and carry their Persona seamlessly.
* The **Badge SDK** gives developers the ability to mint, read, and design custom Badges, allowing communities and projects to capture their own definitions of value.

All relevant smart contracts are public and verified, with both mainnet and testnet deployments available. Developers can query them directly, use RPCs, or build on top of the SDKs.

For transparency, contract addresses are published in the registry:

* T-Rex Passport
  * Mainnet: `0xbbB216C52f5B9095391f463AdC438d65a8aC2242`
  * Testnet: `0x06fAb5a4e177fefE5Cc15dc41C64Ba933021418a`
* T-Rex Badge
  * Mainnet: `0x6F52cCCfAb0712Db45C31863B262e2683097bb5c`
  * Testnet: `0xa51B53Dc3aA7f4ef5fE9bb429521a73f411ad867`

Explorers and dashboards make these interactions transparent, while APIs extend access for off-chain applications. The goal is to remove friction so that developers can integrate T-Rex Personas and Badges in minutes, not months.