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# Paxeer and LayerX

Build EVM applications on Paxeer and connect LayerX activities to its settlement and custody infrastructure.

## How They Work Together

Paxeer is an EVM-compatible Layer 1 with chain ID `125`. LayerX brings agent activity execution, programs, and receipts to applications that use Paxeer for settlement and custody.

Developers use Paxeer’s EVM interfaces for smart contracts and on-chain transactions, and LayerX interfaces for activity execution and application accounting.

| Build with | Capabilities | Developer interfaces |
| --- | --- | --- |
| Paxeer | EVM smart contracts, native assets, transaction execution, and settlement | Ethereum JSON-RPC, Cosmos APIs, and `paxd` |
| LayerX | Agent activities, programs, account operations, and receipts | LayerX agent APIs, SDKs, and human interfaces |

## Settlement on Paxeer

LayerX settlement contracts connect activity execution to Paxeer. Their interfaces cover deposits and custody, checkpoint commitments, guarantor bonds, challenges, withdrawals, and exits.

For an integration, use the contract ABI and deployment address for your environment. Follow the LayerX receipt for the activity and the Paxeer transaction receipt for the corresponding on-chain operation.

## Assets and Fees

PAX pays for EVM transactions on Paxeer. LayerX activities use the LayerX protocol’s accounting and fee schedule. An application that performs both activity execution and on-chain settlement should display the relevant fee for each operation.

## Start Building

- [Build and deploy a Solidity contract with Foundry](https://docs.paxeer.app/foundry), or use the [Hardhat guide](https://docs.paxeer.app/hardhat).

- [Connect a wallet](https://docs.paxeer.app/building-a-frontend) and [read balances, contract state, and transaction receipts](https://docs.paxeer.app/querying-evm).

- Explore the [contract interfaces](https://docs.paxeer.app/contracts) and [native precompiles](https://docs.paxeer.app/precompiles) available to Paxeer applications.

- Use the [network reference](https://docs.paxeer.app/network-parameters) and [node guide](https://docs.paxeer.app/run-node) to configure your development environment.