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The B2B API uses CAIP identifiers for accounts and assets. CAIP gives EVM and non-EVM resources one wire format. Fields that end in AccountId or assetId use CAIP. Do not send bare addresses in these fields. Two deliberate exceptions appear in the B2B API:
  • Enrollment and chain activation accept numeric chainIds. These values select configured chains. They do not identify an account or an asset.
  • EIP-712 requires a bare EVM address in domain.verifyingContract.

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CAIP-10 account forms

CAIP-10 identifies an account. The B2B API uses two forms:

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Chain-agnostic: <namespace>:0:<address>

Use this form when an account has the same address on each chain in a namespace. An EVM externally owned account (EOA) uses this form. The chain reference is the literal string 0 as specified in CAIP-10 §Abstract Account Addresses.
Use this form for end-user wallets (ownerAccountId) and agent wallets (agentAccountId).

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Chain-bound: <namespace>:<chainId>:<address>

Use this form when an account exists on one chain only. Each smart-contract account is chain-bound because its deployment exists on one chain.
Use this form for portfolio smart accounts (SmartAccount.accountId) and withdrawal recipients (recipientAccountId).

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Solana accounts

Solana does not have a chain-agnostic 0 form. Solana accounts use the mainnet CAIP-2 reference as the chain segment. This reference is the chain genesis hash.
Use this form for these accounts:
  • Solana-rooted owner wallets (ownerAccountId, Model B)
  • The pooled agent (agentAccountId)
  • Swig sub-account smart accounts (SmartAccount.accountId)
EVM-rooted Solana enrollment (Model A) keeps the EVM eip155:0:<addr> owner form. Only the returned smart accounts use solana: addresses.

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Rules for each field

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Validation

The API validates and normalizes each CAIP-10 string for its namespace. EVM addresses are not case-sensitive. The API converts them to lowercase. Therefore, uppercase and lowercase EVM addresses are equivalent for lookup. Solana base58 addresses are case-sensitive. The API keeps their case.

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CAIP-19 for Assets

CAIP-19 identifies an asset. The B2B API uses it for strategy allocation assetIds and withdrawal assetIds.

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ERC-20 on EVM

Example for USDC on Ethereum mainnet:

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SPL on Solana

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Common IDs

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Build CAIP strings

Do not manually join CAIP strings in the client. A missing 0x, incorrect case, or incorrect chain reference produces 400 API_400. Use a CAIP-10 or CAIP-19 library. If you cannot use a library, use these canonical forms:
Example for an EVM smart account on Base:

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Exception: EIP-712 verifyingContract

In a signed EIP-712 envelope, domain.verifyingContract is a bare EVM address. It is not a CAIP-10 identifier. EIP-712 requires this form because wallets do not use CAIP for this field. This exception applies only to the signed envelope. Do not use this form for other fields.

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Common errors

  • Do not send bare hex to an *AccountId field. The API rejects bare hex. Convert the value to the correct CAIP-10 form.
  • Do not use eip155:0:<addr> as a withdrawal recipient. A withdrawal recipient must be chain-bound.
  • Do not send a chain-bound EVM owner during enrollment. Use eip155:0:<addr> for an EVM owner. Model B Solana enrollment is the exception. It uses the mainnet solana:5eykt4…:<base58> form.
  • Do not compare raw EVM account strings. Normalize EVM identifiers with a CAIP-10 parser before comparison. Do not convert Solana identifiers to lowercase.