Bridge Integration

Developer guide to bridging ETH, USDC, and XCN between Ethereum Mainnet and Goliath Mainnet — contracts, REST API, and code examples for mobile and web integrators.

The Goliath Bridge moves assets between Ethereum Mainnet (Chain ID 1) and Goliath Mainnet (Chain ID 327) in both directions. This guide is written for external developers — mobile, web, and backend integrators — who want to submit bridge transactions and track them to completion without depending on the Onyx App UI.

The same flows work on testnet, with different chain IDs and contract addresses. See Contracts & Events for both environments.

Supported Assets

Asset	Ethereum → Goliath	Goliath → Ethereum	Ethereum side	Goliath side
ETH	Lock + mint	Burn + release	Native ETH	Bridged ERC-20
USDC	Lock + mint	Burn + release	ERC-20	Bridged ERC-20
XCN	Lock + mint	Signed intent + native transfer	ERC-20	Native gas token

Each direction uses a slightly different transaction shape. See Ethereum → Goliath and Goliath → Ethereum for the exact steps.

Smart-account wallets (Safe, Coinbase Smart Wallet, Biconomy, Alchemy AA, ZeroDev, thirdweb, …) are supported on the XCN withdraw flow via ERC-1271 signatures and ERC-4337 handleOps(...) execution. See Smart Account Integration for the hard rules and worked examples.

Transfer Times and Fees

Direction	Typical time	Fee
Ethereum → Goliath	~5 minutes	Free (gas on Ethereum only)
Goliath → Ethereum	~1 hour*	max(0.25%, minimum fee)

* The Goliath → Ethereum path includes a one-hour security hold before the relayer releases funds on Ethereum.

Goliath → Ethereum Fee Schedule

Token	Fee rate	Minimum fee	Minimum bridge amount
ETH	0.25%	0.003 ETH	0.01 ETH
USDC	0.25%	5 USDC	10 USDC
XCN	0.25%	1,000 XCN	5,000 XCN

The fee is max(amount * 25 / 10000, minFee[token]). Transfers below the minimum bridge amount are rejected. Always call GET /bridge/fee-quote before prompting the user — the canonical values come from the API, not from this document.

Network Endpoints

Goliath Mainnet (Chain ID 327)

Service	URL
EVM JSON-RPC	https://rpc.goliath.net
Block Explorer	https://explorer.goliath.net
Bridge REST API	https://bridge.goliath.net/api/v1

Ethereum Mainnet (Chain ID 1)

Use any public or private Ethereum RPC provider — the bridge has no chain-specific requirements on the Ethereum side.

Contract Addresses (Mainnet)

Contract	Chain	Address
BridgeLock	Ethereum (1)	0xa9fd64b5095d626f5a3a67e6db7fb766345f8092
BridgeMint	Goliath (327)	0x1d14ae13ca030eb5e9e2857e911af515cf5ffff2
Relayer wallet	Goliath (327)	0x90F26908Ee30C8fA6812f6BA66c050a86C8aF6cB

Token addresses and testnet equivalents live in Contracts & Events.

The relayer wallet address is the destination for native-XCN withdrawals (Goliath → Ethereum for XCN only). Always read the current address from POST /bridge/xcn-withdraw-intent — never hardcode it in mobile builds, because it may rotate.

End-to-End Flow at a Glance

Ethereum (1)                               Goliath (327)
============                               ==============

User -> BridgeLock.deposit(...)       [Ethereum tx confirmed]
                                           |
                                           v
                                      Relayer observes Deposit event
                                           |
                                           v
User                              <-  BridgeMint.mint(...)     [Goliath tx confirmed]

                                   ... (1 hour hold for security)

User -> BridgeMint.burn(...)  or  XCN withdraw intent + native transfer
                                           |
                                           v
                                      Relayer observes Withdraw / native tx
                                           |
                                           v
User <-  BridgeLock.release(...)      [Ethereum tx confirmed]

Both legs are triggered by on-chain events (or a signed intent for native XCN). The relayer is an off-chain service operated by the Goliath team — external developers never call its endpoints directly.

Quick Start for Mobile Developers

1. Read Architecture to understand the lifecycle and the three transaction shapes.

2. Pick your direction:

   • Ethereum → Goliath: Ethereum → Goliath guide

   • Goliath → Ethereum (ETH/USDC): Goliath → Ethereum guide

   • Goliath → Ethereum (XCN): Goliath → Ethereum guide

3. Wire up status polling via GET /bridge/status keyed by your origin tx hash.

4. Render history via GET /bridge/history keyed by the user's wallet address.

Index

• Architecture — Contracts, flows, finality, status lifecycle.

• Ethereum → Goliath — Deposit flow with code.

• Goliath → Ethereum — Withdraw flows for ERC-20 and native XCN.

• REST API Reference — All public endpoints.

• Contracts & Events — Addresses, ABIs, events (mainnet + testnet).

• Smart Account Integration — ERC-1271 / ERC-4337 (Safe, Coinbase Smart Wallet, Biconomy, Alchemy AA, ZeroDev, thirdweb).