> For the complete documentation index, see [llms.txt](/llms.txt).

# Scopes (CAIP-2)

MetaMask Connect Multichain uses CAIP standards to identify chains, [accounts](/metamask-connect/multichain/concepts/accounts/), and [sessions](/metamask-connect/multichain/concepts/sessions/).

Traditional single-chain dapps identify networks with a numeric chain ID (for example, `1` for Ethereum Mainnet). That works within EVM ecosystems, but it does not generalize across ecosystems. Solana does not use numeric chain IDs, and a raw value like `1` is ambiguous without an ecosystem context.

Scopes solve this by providing a **universal chain identifier** for a chain or set of chains. When you [connect](/metamask-connect/multichain/reference/methods/#connect) to MetaMask, you pass an array of scopes to declare exactly which chains your dapp needs. When you call [invokeMethod](/metamask-connect/multichain/reference/methods/#invokemethod), you pass a scope to target the correct chain without switching networks.

## Format and examples[​](#format-and-examples "Direct link to Format and examples")

A scope is a chain identifier in `namespace:reference` format, as defined by [CAIP-2](https://github.com/ChainAgnostic/CAIPs/blob/main/CAIPs/caip-2.md). It identifies a specific blockchain across any ecosystem.

- The **namespace** identifies the ecosystem or standard (for example, `eip155` for EVM, `solana`for Solana).
- The **reference** identifies a specific chain within that namespace.

```
// Connect to Ethereum, Polygon, and Solana in a single call
await client.connect(
  [
    'eip155:1', // Ethereum Mainnet
    'eip155:137', // Polygon Mainnet
    'solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp', // Solana Mainnet
  ],
  []
)

// Send an RPC request to a specific chain using its scope
const balance = await client.invokeMethod({
  scope: 'eip155:1',
  request: { method: 'eth_getBalance', params: ['0xab1...', 'latest'] },
})

```

## Supported scopes[​](#supported-scopes "Direct link to Supported scopes")

| Ecosystem | Format               | Examples                                                                                            |
| --------- | -------------------- | --------------------------------------------------------------------------------------------------- |
| EVM       | eip155:<chainId>     | eip155:1 (Ethereum), eip155:59144 (Linea), eip155:137 (Polygon)                                     |
| Solana    | solana:<genesisHash> | solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp (Mainnet), solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1 (Devnet) |

## Common EVM scopes[​](#common-evm-scopes "Direct link to Common EVM scopes")

| Network          | Scope           |
| ---------------- | --------------- |
| Ethereum Mainnet | eip155:1        |
| Linea Mainnet    | eip155:59144    |
| Base Mainnet     | eip155:8453     |
| Polygon Mainnet  | eip155:137      |
| Arbitrum One     | eip155:42161    |
| Optimism         | eip155:10       |
| Sepolia testnet  | eip155:11155111 |

## Next steps[​](#next-steps "Direct link to Next steps")

- [Accounts](/metamask-connect/multichain/concepts/accounts/): Learn how CAIP-10 account IDs extend scopes with addresses.
- [Sessions](/metamask-connect/multichain/concepts/sessions/): Learn how scopes and accounts are grouped into authorized connections.