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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.

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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.

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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)

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.

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End-to-End Flow at a Glance

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:

  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

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