What Is Crosschain Interoperability?

Mar 6, 2026

4 min read

Blockchains are isolated by design. Ethereum doesn't know what's happening on Solana. Base can't read data from Arbitrum. Each network maintains its own state, its own validators, and its own rules.

This isolation is a security feature — but it creates a problem for users who want to move value between them. Crosschain interoperability is the category of protocols, standards, and infrastructure that solves this problem.

Why Blockchains Are Siloed

Each blockchain is essentially a separate database with its own consensus mechanism. Ethereum reaches agreement through proof-of-stake validators. Solana uses a different validator set and a different consensus model. Neither has native visibility into the other's state.

This means an Ethereum smart contract can't natively verify what happened on Solana — it can only see Ethereum transactions. And a Solana program can't read an Ethereum state root.

This silo problem is a feature at the individual chain level (it limits attack surface) but a friction point at the ecosystem level (it fragments liquidity and users).

What Crosschain Interoperability Enables

When crosschain infrastructure is in place, several things become possible:

Asset movement — Moving tokens from one chain to another. This is the most common use case: sending USDC from Ethereum to Base, or ETH from Arbitrum to Solana.

Crosschain messaging — Sending data or triggering actions across chains. A smart contract on one chain can initiate an action on another.

Crosschain swaps — Exchanging one token on one chain for a different token on a different chain, in a single user action.

Unified liquidity — Protocols that pool liquidity across multiple chains, allowing users to access it from wherever they are.

How Crosschain Interoperability Works

There are several technical approaches to crosschain communication:

Bridges with trusted validators — A set of validators monitor both chains and verify cross-chain messages. Funds are locked on the source chain and released (or minted) on the destination. Risk: the validator set is a centralised trust point.

Optimistic verification — Transactions are assumed valid and can be challenged within a window (typically 7 days for optimistic rollups). More trust-minimised but slower.

Intent-based execution — Users specify what they want to receive. Competitive fillers provide the output on the destination chain and are reimbursed by the protocol. This is the model used by Relay: it achieves fast execution (2.7 second median) without requiring the user to trust a specific bridge operator.

Light client bridges — Cryptographic proofs verify the state of one chain inside a smart contract on another chain. Most trust-minimised but computationally expensive.

The Current State of Interoperability

In 2026, intent-based execution has become the dominant model for end-user crosschain activity. It achieves the best combination of speed, safety, and simplicity for most use cases.

Relay operates as intent-based infrastructure across 85+ chains. Applications use Relay to offer crosschain functionality without exposing routing complexity to users — over 200 wallets, DeFi protocols, and consumer apps integrate it.

The longer-term direction of the ecosystem is toward greater abstraction: users shouldn't need to know which chains are involved at all. Chain abstraction — where the crosschain routing is entirely invisible — is where the infrastructure is heading.

Frequently Asked Questions

Is crosschain interoperability the same as bridging?

Bridging is one mechanism for achieving crosschain interoperability — specifically, asset movement. Interoperability is the broader category that also includes messaging, smart contract calls, and data sharing across chains.

Which chains are interoperable with each other?

It depends on the protocol. Major chains — Ethereum, Base, Arbitrum, Optimism, Solana, Polygon — are well-connected through multiple interoperability solutions. Relay supports 85+ chains including many newer networks like Abstract, Berachain, and HyperEVM.

Is crosschain activity safe?

Safety varies significantly by implementation. Intent-based protocols like Relay are non-custodial — no single party holds your funds during execution. Lock-and-mint bridges have a more mixed safety record; several major bridge exploits in prior years involved custodial or centrally-validated architectures.