Packages & Limitations

Relevant CosmJS exports for EVM support and known limitations.

CosmJS EVM support is spread across three packages. Below are the relevant exports and the known limitations when working with EVM-compatible Cosmos chains.

@cosmjs/amino

Export	Purpose
EthSecp256k1Pubkey	Interface for EVM public keys in Amino format
isEthSecp256k1Pubkey()	Type guard for EVM public keys
rawEthSecp256k1PubkeyToRawAddress()	Derive raw address from compressed pubkey (Keccak)
encodeEthSecp256k1Pubkey()	Encode raw pubkey bytes to Amino format
encodeEthSecp256k1Signature()	Encode pubkey + signature to StdSignature
isEthereumSecp256k1Account()	Check if an account uses EVM keys
getAminoPubkey()	Auto-select correct pubkey encoding for an account

@cosmjs/proto-signing

Export	Purpose
DirectEthSecp256k1HdWallet	HD wallet with Keccak signing and EVM HD path
DirectEthSecp256k1Wallet	Single-key wallet with Keccak signing

@cosmjs/crypto

Export	Purpose
keccak256	Keccak-256 hash function
Keccak256	Streaming Keccak-256 hash class

Limitations

• No Amino signing for EVM chains. There is no Secp256k1HdWallet equivalent for EVM keys. Use Direct signing (DirectEthSecp256k1HdWallet) exclusively.
• No 0x-prefixed addresses. CosmJS produces Bech32 addresses for all chains, including EVM ones. If you need the hex Ethereum address, extract the raw 20-byte address and hex-encode it yourself.
• No EVM JSON-RPC. CosmJS communicates over Tendermint/CometBFT RPC, not Ethereum’s JSON-RPC. For eth_sendTransaction or similar calls, use an Ethereum library like ethers.js or viem alongside CosmJS.
• No serialization/deserialization for EVM wallets. Unlike DirectSecp256k1HdWallet, the EVM wallet classes do not support serialize() and deserialize() methods for encrypted storage.