What is the Optimism ERC 721 bridge?

The Optimism NFT Bridge is a protocol that allows users to bridge ERC 721 NFTs from Ethereum Mainnet (Layer 1) to Optimism (Layer 2).

Why trade NFTs on Optimism?

An average transaction on Quix costs less than $0.20 in gas and is up to 100x faster than on Ethereum mainnet. Additionally, Optimism is EVM equivalent, so smart-contracts on the network inherit the security of Ethereum and are written exactly the same way as they are on mainnet. Optimism even uses the same tooling ecosystem as L1 (ENS, Etherscan, Uniswap, Metamask), so the network is easy to adjust to.

How Does the Bridge Work?

When you bridge an NFT from Ethereum, your L1 asset gets locked in a smart contract (which can be found here) and you receive an identical NFT on Layer 2. That “bridged” NFT on layer 2, then acts as a “key” which can be used to unlock the L1 NFT at any time. If you sell or transfer the bridged L2 NFT, then only the new owner will be able to unlock the L1 NFT for themselves.

Follow these steps to bridge any Ethereum NFT you own.

How long does it take to bridge my NFT to L2?

Conservatively 15 minutes, but usually faster.

Where can I find my bridged NFT?

The bridged NFT will appear on your Quix profile at https://qx.app/profile

What will trading bridged NFTs on Quix look like?

All NFTs from a collection, bridged or unbridged, will be displayed on Quix. Each NFT will have an icon in the lower left corner of the asset image indicating what chain the asset is on. The experience trading a bridged NFT will be exactly the same as trading an Optimism-native NFT.

What if I want to bring my NFT back to L1?

You’ll be able to bridge it back to L1 the same way you bridged to L2 at qx.app/bridge. NOTE: Bridging an NFT from Optimism back to Ethereum will take 7 days.

Why does it take 7 days to bridge an NFT back from L2 to L1?

Users are required to wait for a period of one week when moving assets out of Optimism into the Ethereum mainnet. This period of time is called the Challenge Period and serves to help secure the assets stored on an Optimistic Ethereum network. You can find more information about the Challenge Period here.

I need to use my NFT to get access to my community, can I do that with my L2 NFT?

Anything a normal NFT can do, a bridged L2 NFT can do as well. However, devs must do something! The developers of your L1 project will need to make updates so that their features can be accessible via the L2 token, but these edits should be fairly easy for them.

What does Metadata look like for a bridged NFT?

Calling the tokenURI function for an NFT that has been bridged to Optimism will return a URL in the EIP-681 format, rather than a typical IPFS or HTTPS link. The bridged metadata link will start with the ethereum prefix, followed by the contract address, chain ID, function, and token ID.

For example, calling tokenURI on a bridged token might return the following: ethereum:[email protected]/tokenURI?tokenId=1. To get the actual token metadata, you should then call the function tokenURI(1) on the contract 0x099689220846644f87d1137665cded7bf3422747, which can be found on Ethereum chain ID 1, commonly referred to as eth-mainnet.

We use this format so that any metadata changes made to the NFT on L1 are always reflected on the bridged NFT as well. We recommend adjusting to account for this standard if your platform runs an indexer and/or wants to display NFTs that have been bridged to Optimism.

Can I bridge an entire collection at once?

No, only holders can bridge their NFTs and they can only bridge one NFT at a time.

How do I claim my royalties from L2 transactions?

If your royalties are defined on-chain and the payout address is set to an EOA (via contractURI or https://eips.ethereum.org/EIPS/eip-2981), we’ll automatically set the payout address to the same EOA and amount, but on Optimism. You can claim these at any time.

If your royalties are not defined on-chain, or are set to a contract, we’ll need to assign them manually. If the L1 contract is owned by an EOA, then you’ll be able to set your royalties using that address via Quix here [link]. Otherwise, please contact us and we will set them for you.

If you are a collection owner and need to get in touch with our team regarding royalties or collection information, please do so by sending a direct message to @qx_app on Twitter via your collection’s official Twitter account.