In spite of the growing support for the blockchain, Ethereum suffers from an ill-fated problem: scalability. As more people use the network, congestion occurs. And as congestion continues to build, gas fees rise while transaction speeds temper down.

Thankfully, crypto is filled with bright minds. One of the current solutions to save Ethereum from its impending doom are layer 2 networks. Their goal is to reduce transaction speeds and, thus, scale the layer 1 network.

Notably, Polygon and Arbitrum lead the pack. Their ingenuity, combined with their sheer success, are what make these sidechains stand out from the other layer 2 networks.

There are three solutions to set up a Polygon to Arbitrum bridge: Synapse, Celer Network’s cBridge, and Hop Exchange. 

If you use Polygon and Arbitrum already, this article is for you. And even if you don’t, you could learn a thing or two about the networks. Today, I’ll be going in-depth on how to send your coins across networks with the aforementioned tools.

Let’s get into it.

What’s Polygon?

You might’ve heard of Polygon before reading this⁠—if you trade NFTs, then you’ve definitely noticed the purple logo underneath the “Chains” dropdown on OpenSea’s NFT marketplace.

Polygon’s blockchain is known as a Proof-of-Stake (PoS) sidechain and runs parallel to the Ethereum Mainnet. It seeks to solve Ethereum’s inefficiencies in transaction speeds by batching transaction data on the Polygon sidechain, confirming them, then returning the data back to the Ethereum network. 

So instead of processing thousands of transactions per second individually, Ethereum just has to process the refined transaction data in one go. 

The PoS consensus mechanism is how transactions are confirmed and added to Polygon. Validators and delegators are the network’s backbone, as they stake MATIC (Polygon’s native cryptocurrency) to verify new transactions.

In return, they receive a cut of fees and free MATIC.

What’s Arbitrum?

Arbitrum is just like Polygon, but it uses a different technology to address some of the shortcomings of the Ethereum Mainnet.

And this method, called an “optimistic rollup,” compresses thousands of transactions into a single one⁠—it literally “rolls up” data into an individual transaction which is then posted onto the Ethereum Mainnet. 

Optimistic rollups differ from other scaling solutions for their positive outlook (if you could say that). In sum, they assume all transactions on the sidechain are valid, with malicious behaviour reported manually through validators. 

This is why Arbitrium has over 40,000 transactions per second (TPS) compared to Ethereum’s measly 14 TPS.

How do you bridge to Arbitrum?

Before getting into the ‘how”, let’s consider why you should set up a Polygon to Arbitrum bridge.

Bridges are one of the core components of Ethereum’s layer 2 solutions. They migrate cryptocurrencies and other crypto assets from one blockchain network onto the next.

If I bought a couple of ETH on Polygon but wanted to use it on the Arbitrum network, I would have to migrate my ETH from the Polygon sidechain onto the Arbitrum network. 

There are three options for a Polygon to Arbitrum bridge:

1. Synapse
2. Hop Exchange
3. Celer Network’s cBridge

Let’s dive into each one.

Synapse, the leading Polygon to Arbitrum bridge

Synapse Protocol is the most widely used cross-chain network in the crypto sphere. Just take a look at the stats: over 110K ETH has been instantly bridged to and from Arbitrum in late 2021⁠—quite impressive if you ask me.

To form a Polygon to Arbitrum bridge, follow these steps:

1. Go to Synapse Protocol’s platform
2. Connect your wallet
3. Select which chain to bridge from (‘1’) and which to bridge to (‘2’). In this case, you’ll be selecting Polygon and Arbitrum, respectively.
4. Select the asset you wish to bridge (‘3’). The only assets you can choose from are stablecoins, but we’ll get into that later.
5. Enter the amount you wish to transfer. Remember, don’t put in the max amount as you need some spare change for fees.
6. Click Bridge Token
7. You’ll get a pop-up from MetaMask asking you to approve the transaction. Click Confirm.

Now all you have to do is wait a few minutes, and you’ll get your cryptocurrency bridged from the Polygon network onto the Arbitrum network. It’s that easy.

I mentioned in the steps that you can only bridge stablecoins on this platform. So if you have ETH and want to transfer it using a Polygon to Abitrum bridge, you’ll first have to exchange it on a DEX or CEX for one of the supported stablecoins, bridge it on Synapse, then swap the stablecoin to ETH on Arbitrum.

cBridge by the Celer Network, a cross-chain solution

Celer Network: an optimized layer 2 solution enabling DeFi, blockchain gaming, NFTs, and other handy crypto tools and software across multiple blockchains.

Out of their product arsenal, the cBridge extension is perfect for those who want to transfer their tokens across networks in a Polygon to Arbitrum bridge. It’s pretty similar to Synapse, as the steps are almost the same:

1. Access the cBridge tool
2. Click the blue Connect Wallet button at the bottom and follow the prompts
3. Select which chain to bridge from (‘1’) and which to bridge to (‘2’). In this case, you’ll be selecting Polygon and Arbitrum, respectively.
4. Select the asset you wish to bridge (‘3’). cBridge has a decent line-up of tokens you can transfer compared to Synapse
5. Enter the amount you wish to transfer. Remember, don’t put in the max amount as you need some spare change for fees.
6. Click Transfer
7. You’ll get a pop-up from MetaMask asking you to approve the transaction. Click Confirm.

I wasn’t kidding when I said it’s almost identical to Synapse 😂

One thing to keep in mind: Celer Network’s cBridge extension supports two stablecoins (USDC and USDT) with other options like WETH, DF, and USX.

Hop Exchange, a scalable rollup-to-rollup bridge

Hop Exchange is another contender in the Polygon to Arbitrum bridge kingdom. This solution was built specifically for bridging tokens from one rollup layer 2 blockchain onto the next.

And surprise, surprise! The steps are pretty much the same:

1. Click this link to enter the Hop Exchange website
2. Hit the Connect a Wallet button in the top right, then follow the prompts
3. Once your wallet is connected, select which chain to bridge from (‘1’) and which to bridge to (‘2’). In this case, you’ll be selecting Polygon and Arbitrum, respectively.
4. Select the asset you wish to bridge (‘3’). Hop Exchange facilitates ETH, MATIC, USDC, USDT, and DAI transfers.
5. Enter the amount you wish to transfer. Remember, don’t put in the max amount as you need some spare change for fees.
6. Click Send
7. You’ll get a pop-up from MetaMask asking you to approve the transaction. Click Confirm.

Hop Exchange is perfect for those sending ETH from Polygon to Arbitrum without having to swap it for a stablecoin.

How long does it take to bridge to Polygon?

Don’t worry anon, transferring tokens from Polygon to Arbitrum isn’t too bad, time-wise.

On average, a Polygon to Arbitrum bridge takes only a few minutes. Maybe five if we’re really pushing it.

How much does it cost to bridge to Arbitrum?

Want the short answer? It depends on the solution you use.

From my tests, I found that cBridge was marginally cheaper than Synapse, and Hop Exchange is the most affordable for sending ETH as you don’t have to swap it out for a stablecoin. All you’re really paying for are layer 2 gas fees anyways.

Summary

Setting up a Polygon to Arbitrum bridge is easier than you may think. 

All you have to do is:

1. Access Synapse, Celer Network’s cBridge, or Hop Exchange’s platform
2. Connect your wallet
3. Select Polygon in the “From” dropdown menu and Arbitrum in the “To” menu
4. Select the coin you will transfer
5. Enter the amount
6. Accept the transaction in your wallet