How to use MetaMask Bridges

Want to bridge to a network you've never used before? Read this first!

Before you move your funds onto another network, remember that you'll need native tokens on that network in order to use them further. As we don't currently support bridging BNB, this means you'll need to get these into your wallet on this network either through an on-ramp (buying with conventional currency, and having the tokens deposited into your wallet), having tokens sent to your wallet, or buying from an exchange that supports the network and transferring them.

 

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Launching as a beta feature integrated into the MetaMask Portfolio Dapp, MetaMask Bridges does exactly what it says on the tin: it pulls together bridging quotes for you to choose from. From here, you can pick the quote that's best for you and move your tokens to the network you need.

Think of it as an aggregator of aggregators, or meta-aggregator. It’s analogous to visiting travel sites that find you the cheapest flight from numerous airlines, or — slightly closer to home — using MetaMask Swaps to find you the cheapest token swap quote from decentralized exchanges.

 

What is a bridge?

A bridge allows you to transfer your tokens between different blockchain networks. For example, perhaps you want to use a dapp or a game on the Polygon network, but most of your funds are on Ethereum mainnet. You can use a bridge to transfer some ETH, USDC, or other tokens from Ethereum to Polygon — retaining their value — and start to use them with dapps on Polygon.

To dive a bit deeper:

At their most basic level, bridges are platforms with contracts on the chains you're transferring to and from. Though the exact system varies, each bridge has a mechanism to validate your deposit on one network and issue equivalent tokens on another network.

When you request to move Ethereum from Mainnet to Polygon, for example, the first thing the bridge will need to do is have you deposit the ETH to the bridge. The bridge will prompt you to sign a transaction to send the tokens to their address (for tokens other than ETH, this assumes you've already signed an approval granting it access to your tokens).

 

BridgeV1.png

 

The deposit may be validated in a few different ways depending on the bridge, but this process essentially buys you the right to have your target address credited with the agreed amount of tokens (that is: the token you're bridging to). The bridge honors this request by minting or sending the tokens to the account you specified on the destination network.

 

Where can I find it?

You can find MetaMask Bridges feature within the Portfolio Dapp, available at portfolio.metamask.io.

 

How does it work?

MetaMask Bridges takes the data you input and runs it through existing bridge aggregators. For every transaction, you’ll need a:

  • Source network
  • Destination network
  • Token type and quantity.

Once we're finished trawling the aggregators, you’ll be presented with a recommended quote, as determined by our algorithm. If you want to choose an alternative route, you’ll be able to view and select other quotes too.

Additionally, although we request your bridge transfer through an aggregator, we’re also only using the aggregators to access a select list of bridges which meet our requirements for trust minimization.

Here’s our step-by-step guide:

  1. Make sure your wallet is connected and that you’ve selected the account that has the tokens you want to bridge.
  2. Select the network from which you want to move tokens under the ‘From this network’ field.
  3. Input the details of the token you want to bridge under ‘You send’. The drop-down list in this field is divided into tokens that are ‘Able to bridge’ and those that you’re ‘Unable to bridge’. The category each token belongs to depends on:
    • Whether we currently support that token
    • Whether you hold that token in your wallet.
  4. Pick the network to which you want to bridge the tokens under ‘To this network’.

    When you input a token and an amount to send, the aggregator will start to find quotes. Once it’s done, you’ll be able to see how much of the token you’ll receive on the destination network, and your quote listed under ‘Recommended Bridge’ below.

  5. Assess the quote by clicking the drop-down arrow in the top right of the quote. Here you can see estimated timings and fees. The quote will refresh every minute to make sure you’re getting up-to-date information.
  6. If you want to view other quotes, hit ‘Choose a different bridge’ in the top-right of the quote field. Click on one to select it.
  7. When you’re happy with the quote, click the ‘Confirm Bridge’ button below the quote. This will call up a window which asks you to sign a message using your wallet. Follow the prompt and MetaMask will open to allow you to do so, and then proceed through to initiate the bridge.

 

What are the benefits?

We’re continually working to make MetaMask a flexible, empowering passport to access all that web3 has to offer. Efficiently bridging tokens with as little risk as possible is a key pillar of your independence and agency on the decentralized web, where you should have full control of how and where you manage your digital assets and identity. This is why MetaMask, in contrast to the ‘walled gardens’ of web2, will always be free, and why we cannot and will not try and stop you or penalize you if you’d prefer to conduct your activities elsewhere.

A similar logic applies to moving assets between blockchains. Enter bridging, and one of the reasons we want to provide the most seamless, accessible bridging platform we can for MetaMask users.

Here’s why we think you’ll like it:

  • We do the legwork: No more trawling the web to find the cheapest aggregator that also supports the tokens and networks you want.
  • Safety: Only bridge using platforms which have passed our vetting process, ensuring we’re only presenting you with the most secure platforms we can find.
  • Transparency: We will always make you aware of the risks of every transaction and provide you with our best estimates of expected duration and price.
  • Reliability: If you can see an option in the aggregator for a certain path or token, you will be able to use it, and with a high expectation of success. We’ll never pursue choice–unsustainably adding more networks and tokens–at the cost of reliability and quality.

 

FAQs

What networks are supported?

Initially, you’ll be able to bridge between:

  • Ethereum mainnet
  • Polygon
  • BNB Smart Chain
  • Avalanche.
What tokens are supported?

Native tokens on Ethereum (ETH) and Polygon (MATIC) and Avalanche (AVAX), and USDC, USDT, and DAI on all networks.

Does MetaMask take custody of my funds at any point?

No, we work with third parties to bridge your tokens between networks.

Do you make money from this?

No. As this is a beta release, we are not adding any charges. When you use MetaMask Bridges, you pay for:

  • Gas fees on the source network
  • The difference in the value of the token you send vs. the value of tokens you receive on the destination network. This includes any fees charged by the bridge providers, as well as gas fees on the destination network).
I haven't received my tokens in the time I should have. What should I do?

The time we quote is an estimate, and delays can happen for several reasons, such as a change in network conditions. In the majority of cases, the bridge transfer is just delayed and your transfer will still go through automatically.

If you’ve already waited over three hours and your transfer is still in progress, please get in touch with MetaMask Support by clicking the ‘Start a Conversation’ button on our support landing page. If we’re unable to troubleshoot the problem, we will then recommend that you get in touch with the bridge’s support to look into getting your transaction unstuck.

What aggregators and bridges do you use?

As we described above, our platform sources bridging options through two stages:

  • Aggregators, through which we access a selection of;
  • Bridge providers, the platforms that actually execute the bridge.

The aggregators we use are LI.FI and Socket. The bridge providers we access through these aggregators are:

  • Hop
  • Connext
  • Celer cBridge
  • Polygon PoS Bridge
What is the maximum transaction size?

As MetaMask Bridges is currently in beta, the maximum value you can bridge at a time is $10,000.

Something went wrong with my transfer. What do I do?

Don't panic! Just get in touch with Support via the 'Start a Conversation' button on the homepage of this site.

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