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CAIP-2 is a Chain Agnostic Improvement Proposal that defines a single text format for naming a blockchain network: namespace:reference. The namespace names the chain family, and the reference names the network inside that family. Because the format is the same for every ecosystem, one parameter or one result field can carry a network on any chain without a per-chain special case. The hosted wallet connector speaks CAIP-2 in two places: the networks parameter that restricts which networks a user may connect on, and the network redirect param (or networkId on the headless connected message) that reports which network the user ended up on.

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Format

A CAIP-2 id joins a namespace and a reference with a colon:
The namespace is 3 to 8 lowercase letters, digits, or hyphens; the reference is 1 to 32 characters and may include underscores and mixed case. Some references are case-sensitive — Solana’s is base58 — so treat ids as opaque strings and compare them exactly, never case-insensitively.

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Ids for common networks

EVM networks use the eip155 namespace with the decimal chain id as the reference: Solana and Bitcoin derive the reference from the network’s genesis hash — the first 32 characters of it — so the same id identifies the network no matter which RPC or index a wallet used to learn it: Any eip155 chain works the same way: take its decimal chain id and prefix it with eip155:. The full namespace registry and the per-family derivation rules live in the CAIP-2 specification and the linked namespace profiles.

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Where the connector uses it

  • Filtering (networks): pass a comma-separated list of ids to offer only those networks, for example ?networks=eip155:137,solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp. See the parameter table on the overview page.
  • Results (network, networkId): a successful connect reports the network the wallet is on, or the network picked for a manually entered address, as a CAIP-2 id — network on the redirect and networkId on the headless connected message.
The connector omits the id entirely when it cannot name one rather than guessing — an unknown network or a wallet that reports none means an absent network, not a wrong one. Treat the field as optional everywhere you read it.
Last modified on October 20, 2026