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FAQ

Getting Started​

What is VIA Labs?​

VIA Labs provides cross-chain communication infrastructure that enables direct smart contract messaging between blockchains. Your contract on one chain sends a message — data, value, instructions — and your contract on another chain receives and processes it.

How do I send a cross-chain message?​

  1. Copy the VIA Labs base contract into your project (see Contract Source)
  2. Inherit the ViaIntegrationV1 base contract in your smart contract
  3. Call messageSend() to send messages to other chains
  4. Implement messageProcess() to handle incoming messages

See the Hello World quickstart for a complete walkthrough.

What programming languages are supported?​

VIA Labs currently supports Solidity for EVM chains. Support for Aiken (Cardano) and Compact (Midnight) is in development.

How many networks are supported?​

VIA Labs supports 140+ public and private networks. See the Supported Networks page for the full list.

Gas & Pricing​

How are cross-chain fees calculated?​

The sender pays for both source and destination chain gas in a single transaction on the source chain. There are no separate protocol fees — all costs are bundled into native gas. See Fees & Gas for detailed breakdowns.

Ethereum Exception

When receiving cross-chain messages on Ethereum, the developer's deployed contract must hold wrapped ETH (WETH) to cover destination gas costs. This is specific to Ethereum only — on all other chains, the source gas fees cover destination execution automatically.

Who pays for destination chain gas?​

The sender pre-pays destination chain gas as part of the source chain transaction. The messageSend() function automatically estimates the required amount. The protocol handles execution on the destination chain.

Are there any protocol fees?​

No separate protocol fees. All costs are covered by the native gas you pay when sending a message. This includes both chain execution costs and network operational costs — a single, transparent fee with no hidden charges.

Configuration​

Can I send arbitrary data cross-chain?​

Yes. The messageSend() function accepts any ABI-encoded payload. You can send tokens, NFT metadata, strings, structs, sensor data, oracle feeds, governance votes, or any data your application needs.

Can I restrict which chains my contract communicates with?​

Your contract can only communicate with contracts that you have explicitly deployed and configured. When you call setMessageEndpoints(), you define exactly which contract addresses on which chains are authorized to send and receive messages. No other contracts can interact with yours — cross-chain communication is restricted to the endpoints you configure.

Do I need to deploy on every chain I want to communicate with?​

You need a contract deployed on each chain you want to send messages to or receive messages from. Each deployment is configured to recognize its counterparts on other chains via setMessageEndpoints().

Security​

How are cross-chain messages validated and secured?​

VIA Labs uses a three-layer security model. Every message must be independently validated by:

  1. VIA Layer — Protocol-level validation by the VIA network
  2. Chain Layer — Native chain verification using on-chain data
  3. Project Layer — Per-project access control defined by the developer

A message is only executed on the destination chain after passing all three layers. See the Technology Overview for details.

Has the protocol been audited?​

For the latest security information and audit reports, visit the VIA Labs main site.

Troubleshooting​

How long does a cross-chain message take?​

Between 5 seconds and 5 minutes depending on block time and finality. Most transactions settle within 1 minute after being submitted on the source chain.

My message hasn't arrived. What should I check?​

  1. Verify the source transaction was confirmed on-chain
  2. Check that both contracts are configured with the appropriate chain IDs
  3. Ensure the destination contract has the correct permissions set
  4. Visit Troubleshooting for debugging steps, or check your transaction on VIA Scan

Can a message fail on the destination chain?​

Yes. If the destination contract reverts (e.g., due to a logic error, insufficient permissions, or an incorrect payload), the message will not be processed. Check your contract's messageProcess() implementation for potential revert conditions.