Running a Relayer

The Across V3 Relayer is a Node.js-based system that enables users to operate their own relay infrastructure. The complete source code is available in the relayer-v3 GitHub repository.

System Requirements

Component	Minimum
CPU	64-bit Dual Core @ 2+ GHz
RAM	4 GB
OS	UNIX-like (GNU/Linux, macOS)

Installation

Clone the repository and set up your environment:

git clone https://github.com/across-protocol/relayer-v3.git
cd relayer-v3
touch .env
chmod 0600 .env

Your .env file stores sensitive configuration. Restrict permissions to protect private keys or mnemonics.

Core Configuration

Essential Environment Variables

Variable	Description
`SECRET`	Path to private key or mnemonic file
`RPC_PROVIDER_*`	RPC endpoints for supported chains
`RPC_PROVIDERS`	Provider preference ordering
`SEND_RELAYS`	Enable transaction submission (default: `false`)
`MAX_RELAYER_DEPOSIT_LOOK_BACK`	Lookback window in seconds

Gas Configuration

Variable	Description
`MAX_FEE_PER_GAS_SCALER_*`	Per-chain gas fee multipliers
`PRIORITY_FEE_SCALER_*`	Priority fee adjustments

Operational Workflow

Simulate first — run with SEND_RELAYS=false to review transactions before going live:

SEND_RELAYS=false yarn relay

Review the simulated transactions and token approvals.
Go live once you're satisfied:

SEND_RELAYS=true yarn relay

The relayer identifies unfilled deposits across chains and attempts to fill them when your token balances permit.

Advanced Features

Redis Caching

Redis caching significantly improves performance by storing RPC responses. Configure it via the REDIS_URL environment variable.

Inventory Management

Relayers can configure automatic rebalancing across chains using a JSON configuration that specifies:

Target allocation percentages per token and chain
WETH wrapping/unwrapping thresholds
Intelligent repayment chain selection

Supported Tokens

WETH, USDC, DAI, USDT, WBTC, UMA, ACX, BAL, SNX, and POOL.

Relayers receive compensation through root bundles — a set of three Merkle roots containing all information necessary to refund relayers who fulfilled a deposit during a given block range. Root bundles are published every 1.5 hours minimum. Relayers choose their repayment chain, which affects how liquidity provider fees are distributed.

Security Considerations

The relay bot requires in-memory access to private keys for transaction signing. Follow these best practices:

Deploy in isolated environments
Use key-based authentication for remote access
Restrict filesystem permissions on secret files
Maintain secure offline backups of key material
Limit exposure of systems with raw disk access