What are the best blockchain bridges?

As challengers to Bitcoin and Ethereum have emerged so have solutions to bridge between the growing number of layer 1 chains.

Solana

Solana has huge appeal as a layer one chain given the significant throughput it can achieve, with 50,000 transactions per second, compared to Ethereum with just 30. As Solana and its ecosystem have developed the need for bridges quickly emerged.

Wormhole is one of the most Solana bridges providing a cross-chain link to Ethereum. It uses the lock-and-mint approach, described above, listening out for transactions from each side of the bridge, locking up funds and minting an equivalent amount on the other side as wrapped version.

The other natural off-chain destination for Solana assets is Bitcoin and similar PoW chains. REN VM Bridge again uses the lock-and-mint approach to bridge BTC, BCH, ZEC and DOGE.

Avalanche

Avalanche is considered one of the genuine challengers to Ethereum, as similar to Solana, it offers improved throughput. You can bridge any ERC20 token to Avalanche and back using the Avalanche Bridge.

Polkadot

Polkadot provide an interesting dimension to the interoperability debate, positioning itself as the blockchain of blockchains, or layer 0. This solves the cross-chain problem because it creates a broader environment with which compatible blockchains can exist, built using the single Polkadot framework.

Unless, or until, all blockchains are built on Polkadot, the cross-chain issue will still persist, so there are bridging solutions for Polkadot:

• Interlay – Bridging Polkadot and Bitcoin using PolkaBTC
• Snowfork – A general purpose bridge between Polkadot and Ethereum for ERC20 assets and Smart Contracts
• Darwinia – Using a light client approach for native verification on Ethereum and a number of other popular chains.

Terra

Terra is a blockchain protocol supporting decentralised Stablecoins pegged to fiat currencies. It has seen significant increase in use given very generous returns from applications like Anchor with a 20% APY. 

Naturally Ethereum users want to get in on that action so the Terra Bridge is very popular, enabling holders of wrapped versions of Terra assets like Luna, to swap for native versions. Terra Bridge also supports assets from Binance Smart Chain and Cosmos.

Chain Agnostic

ChainBridge provides a chain agnostic approach to bridging, but can only do so by using an off-chain approach requiring trust. Events on a source chain are routed to the destination chain through trusted (off-chain) relayers who, between them, verify the data:

• Listener: extract events & construct a message
• Router: passes the message on
• Writer: interpret & and submit messages to the destination chain

Though ChainBridge aspires to a more decentralised model, it suffers the same problem as Bitgo and custodial bridges – they are counter to the decentralised principles of blockchains. 

A centralised service verifying data is a single point of failure because it can censor a transaction or simply abuse the trust that you have to place in them.