Offline Signers

An OfflineSigner is the interface CosmJS uses to abstract over any source of signatures. It doesn’t matter whether the private key lives in memory, in a browser extension, or on a hardware device — as long as it implements OfflineSigner, it works with SigningStargateClient.

type OfflineSigner = OfflineAminoSigner | OfflineDirectSigner;

There are two flavors, matching the two Cosmos signing modes:

OfflineDirectSigner (Protobuf / Direct)

The modern default. Signs raw Protobuf-encoded bytes. Preferred for new applications.

interface OfflineDirectSigner {
  readonly getAccounts: () => Promise<readonly AccountData[]>;
  readonly signDirect: (
    signerAddress: string,
    signDoc: SignDoc,
  ) => Promise<DirectSignResponse>;
}

OfflineAminoSigner (Amino JSON)

The legacy format. Signs a deterministic JSON representation. Required for Ledger hardware wallets and some older chains.

interface OfflineAminoSigner {
  readonly getAccounts: () => Promise<readonly AccountData[]>;
  readonly signAmino: (
    signerAddress: string,
    signDoc: StdSignDoc,
  ) => Promise<AminoSignResponse>;
}

The “offline” in the name means the signer itself never needs network access. It only receives bytes and returns a signature. The client handles everything else — querying account state, building the transaction, and broadcasting.

Signer Summary

Signer	Use Case	Package
`DirectSecp256k1HdWallet`	Scripts, backends, tests	`@cosmjs/proto-signing`
`Secp256k1HdWallet`	Amino signing, legacy chains	`@cosmjs/amino`
`window.keplr.getOfflineSigner()`	Browser apps with Keplr	(provided by extension)
`LedgerSigner`	Hardware wallet signing	`@cosmjs/ledger-amino`

All of these produce an OfflineSigner. All of them work with SigningStargateClient.connectWithSigner. The signing client doesn’t know or care where the signature comes from — it just needs something that implements the interface.

CosmJS

Concepts

Guides

API Reference

OfflineDirectSigner (Protobuf / Direct)

OfflineAminoSigner (Amino JSON)

Signer Summary

​OfflineDirectSigner (Protobuf / Direct)

​OfflineAminoSigner (Amino JSON)

​Signer Summary

OfflineDirectSigner (Protobuf / Direct)

OfflineAminoSigner (Amino JSON)

Signer Summary