> For the complete documentation index, see [llms.txt](https://docs.nexus.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.nexus.xyz/network/building-on-nexus/tokens-and-bridges/bridging.md).

# Bridging

$NEX moves between Ethereum and BSC via a Hyperlane Warp Route. On Ethereum, $NEX is locked in a collateral contract. On BSC, a synthetic $NEX is minted 1:1 against the locked balance.

You can bridge $NEX between Ethereum and BSC: [Nexus Hyperlane Warp Route](https://nexus.hyperlane.xyz/?origin=ethereum\&originToken=NEX\&destination=bsc\&destinationToken=NEX).

**Ethereum → BSC**

1. Deposit ERC-20 $NEX into the Hyperlane collateral contract on Ethereum.
2. Hyperlane validators attest to the deposit (6-of-9 multisig threshold).
3. Synthetic $NEX is minted on BSC and delivered to your wallet.

**BSC → Ethereum**

1. Synthetic $NEX is burned on BSC.
2. Hyperlane validators attest to the burn (4-of-6 multisig threshold).
3. ERC-20 $NEX is released from the collateral contract on Ethereum and delivered to your wallet.

**Contract addresses**

| Contract          | Ethereum                                                  | BSC                                                      |
| ----------------- | --------------------------------------------------------- | -------------------------------------------------------- |
| Warp Route token  | `0xb71183f48F7f7789D40551149bE28a51f9A97F9A` (collateral) | `0x365DE036A1F7dcCb621530d517133521debB2013` (synthetic) |
| $NEX ERC-20       | `0xf57D49646621F563b0B905aFc8336923AC569Ec5`              | —                                                        |
| Hyperlane Mailbox | `0xc005dc82818d67AF737725bD4bf75435d065D239`              | `0x2971b9Aec44bE4eb673DF1B88cDB57b96eefe8a4`             |

The collateral contract is a TransparentUpgradeableProxy pointing to the Hyperlane canonical HypERC20Collateral implementation. The BSC synthetic is a TransparentUpgradeableProxy pointing to the Hyperlane canonical HypERC20 implementation. Both are verified on Etherscan and BscScan.

**Fees and timing**

| Parameter              | Value                                                                                  |
| ---------------------- | -------------------------------------------------------------------------------------- |
| Bridge fee (ETH → BSC) | 6 bps + gas fees on both source and destination chains                                 |
| Bridge fee (BSC → ETH) | Gas fees on both source and destination chains                                         |
| Transfer time          | Typically under 5 minutes. Depends on validator attestation and source-chain finality. |

**Security**

The bridge uses Hyperlane's Interchain Security Module (ISM) stack:

* ETH → BSC: 6-of-9 validator multisig with dual MerkleRoot and MessageId verification.
* BSC → ETH: 4-of-6 validator multisig with dual MerkleRoot and MessageId verification.

Both warp route contracts are owned by the Nexus Foundation multisig. Proxy upgrades are controlled by the Foundation multisig via OpenZeppelin ProxyAdmin contracts.

**Troubleshooting**

Transfer pending — Transfers require attestation from Hyperlane validators after source-chain finality. If pending for more than 10 minutes, check the [Hyperlane Explorer](https://explorer.hyperlane.xyz/).

Insufficient gas — You need gas tokens on the source chain: ETH for Ethereum → BSC, BNB for BSC → Ethereum.

Transaction reverted — Check that you have approved sufficient token allowance for the Warp Route collateral contract (Ethereum side) and have enough gas on the source chain.

For Hyperlane protocol details, see [Hyperlane documentation](https://docs.hyperlane.xyz/).


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