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Overview

The chain status endpoint provides information about all blockchain chains configured in your Lasso RPC instance.

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Endpoint

GET /api/chains

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Response

Returns a JSON object containing an array of configured chains:
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chains
array
required
Array of chain configuration objects

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Response Example

{
  "chains": [
    {
      "chain_id": "1",
      "name": "Ethereum Mainnet",
      "chain_name": "ethereum",
      "supported": true
    },
    {
      "chain_id": "137",
      "name": "Polygon",
      "chain_name": "polygon",
      "supported": true
    },
    {
      "chain_id": "42161",
      "name": "Arbitrum One",
      "chain_name": "arbitrum",
      "supported": true
    }
  ]
}

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Use Cases

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Discover Available Chains

Query which chains are configured and ready to use: 
curl http://localhost:4000/api/chains

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Validate Chain Configuration

Check if a specific chain is configured before making RPC requests: 
# Check if Ethereum is configured
chains=$(curl -s http://localhost:4000/api/chains)
has_ethereum=$(echo $chains | jq '.chains[] | select(.chain_name=="ethereum") | .chain_id')

if [ -n "$has_ethereum" ]; then
  echo "Ethereum is configured with chain_id: $has_ethereum"
fi

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Dynamic Client Configuration

Use this endpoint to dynamically configure multi-chain applications: 
const response = await fetch('http://localhost:4000/api/chains');
const { chains } = await response.json();

// Build RPC endpoints for each chain
const rpcEndpoints = chains.reduce((acc, chain) => {
  acc[chain.chain_name] = `http://localhost:4000/rpc/${chain.chain_id}`;
  return acc;
}, {});

console.log(rpcEndpoints);
// {
//   ethereum: 'http://localhost:4000/rpc/1',
//   polygon: 'http://localhost:4000/rpc/137',
//   arbitrum: 'http://localhost:4000/rpc/42161'
// }

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Chain Name vs Chain ID

Lasso RPC supports referencing chains by both their numeric chain_id and their chain_name:
  • chain_id: Standard EVM chain identifier (e.g., 1, 137, 42161)
  • chain_name: Human-friendly identifier used in configuration files (e.g., ethereum, polygon, arbitrum)
Both can be used in RPC endpoint paths: 
# Using chain_id
curl -X POST http://localhost:4000/rpc/1 \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

# Using chain_name (if supported by your configuration)
curl -X POST http://localhost:4000/rpc/ethereum \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

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Notes

  • The list of chains is determined by your configuration file
  • All returned chains have supported: true as unsupported chains are not included in the response
  • Chain configurations are loaded at startup and do not change without restarting the instance
  • This endpoint is useful for service discovery in multi-chain applications