beefy_getFinalizedHead - Moonriver RPC Method

Returns the block hash of the latest BEEFY-finalized block on Moonriver. BEEFY (Bridge Efficiency Enabling Finality Yielder) provides additional finality proofs that are optimized for light clients and cross-chain bridges, using compact aggregated signatures instead of full GRANDPA justifications.

Why Moonriver? Build on the Moonbeam canary network on Kusama for real-world testing of EVM dApps with Moonbeam code ships here first, full EVM compatibility on Kusama, 80% fee burn mechanism, and XCM cross-chain messaging.

When to Use This Method

beefy_getFinalizedHead is important for dApp developers testing on Kusama, early adopters, and teams requiring production-ready experimentation:

• Cross-Chain Bridges — Verify finality proofs efficiently for bridge operations on production-grade dApp testing, early feature deployment, and Kusama-based EVM applications
• Light Clients — Verify finality without downloading full GRANDPA justifications
• Trustless Bridges — Generate compact finality proofs that can be verified on external chains
• Bridge Monitoring — Track BEEFY finality progress relative to GRANDPA finality

Code Examples

Common Use Cases

1. Bridge Finality Verification

Verify BEEFY finality before relaying messages on a cross-chain bridge:

async function verifyBridgeFinality(api, targetBlockHash) {
  const beefyHead = await api.rpc.beefy.getFinalizedHead();
  const beefyBlock = await api.rpc.chain.getBlock(beefyHead);
  const beefyNumber = beefyBlock.block.header.number.toNumber();

  const targetBlock = await api.rpc.chain.getBlock(targetBlockHash);
  const targetNumber = targetBlock.block.header.number.toNumber();

  if (beefyNumber >= targetNumber) {
    console.log(`Block #${targetNumber} has BEEFY finality — safe to relay`);
    return true;
  } else {
    console.log(`Waiting: BEEFY at #${beefyNumber}, target at #${targetNumber}`);
    return false;
  }
}

2. BEEFY vs GRANDPA Finality Monitor

Track the gap between the two finality gadgets:

async function monitorFinalityGadgets(api) {
  setInterval(async () => {
    try {
      const [beefyHead, grandpaHead] = await Promise.all([
        api.rpc.beefy.getFinalizedHead(),
        api.rpc.chain.getFinalizedHead()
      ]);

      const [beefyBlock, grandpaBlock] = await Promise.all([
        api.rpc.chain.getBlock(beefyHead),
        api.rpc.chain.getBlock(grandpaHead)
      ]);

      const beefyNum = beefyBlock.block.header.number.toNumber();
      const grandpaNum = grandpaBlock.block.header.number.toNumber();
      const lag = grandpaNum - beefyNum;

      console.log(`GRANDPA: #${grandpaNum} | BEEFY: #${beefyNum} | Lag: ${lag} blocks`);
    } catch (error) {
      console.error('Monitor error:', error.message);
    }
  }, 12000);
}

BEEFY vs GRANDPA Finality

Availability

BEEFY is enabled on Polkadot and Kusama relay chains and some parachains. If BEEFY is not active on the chain you are querying, this method will return an error. Check chain documentation or try calling the method to confirm availability.

Error Handling

Related Methods

• chain_getFinalizedHead — Get GRANDPA finalized head
• grandpa_roundState — Monitor GRANDPA consensus state
• chain_subscribeFinalizedHeads — Subscribe to GRANDPA finalized blocks