Provider Library for Cosmos Extension for Metamask

Snapper is a utility library for interacting with the official Cosmos Extension for Metamask.

Global Provider (Drop In Replacement for window.keplr)

Add the provider as a global object within your dApp.

import { CosmosSnap } from "@cosmsnap/snapper";
window.cosmos = new CosmosSnap();

const memo = "Hello from Metamask!";

let offlineSigner = await window.cosmos.getOfflineSigner("cosmoshub-4");

let wallet = await window.cosmos.getAccount("cosmoshub-4");

// Create a send token message
const msg = {
    typeUrl: "/cosmos.bank.v1beta1.MsgSend",
    value: {
    fromAddress: wallet.address,
    toAddress: "cosmos123456789",
    amount: [
        {
        denom: "uatom",
        amount: "10000",
        },
    ],
    },
};

// Create fee
const fee = {
    amount: [],
    gas: "200000",
};

const signingClient = await SigningStargateClient.connectWithSigner(
    "https://rpc-cosmoshub.whispernode.com:443",
    offlineSigner
);

const result = await signingClient.sign(wallet.address, [msg], fee, memo);

Use in development mode. Note: You must run the snap locally for this to run properly.

window.cosmos.changeSnapId("local:http://localhost:8080");

Structure of the provider.

export interface SnapProvider {
  experimentalSuggestChain(chainInfo: ChainInfo): Promise<void>;
  signAmino(
    chainId: string,
    signer: string,
    signDoc: StdSignDoc,
  ): Promise<AminoSignResponse>;
  signDirect(
    chainId: string,
    signer: string,
    signDoc: {
      /** SignDoc bodyBytes */
      bodyBytes?: Uint8Array | null;

      /** SignDoc authInfoBytes */
      authInfoBytes?: Uint8Array | null;

      /** SignDoc chainId */
      chainId?: string | null;

      /** SignDoc accountNumber */
      accountNumber?: Long | null;
    },
  ): Promise<DirectSignResponse>;
  sendTx(
    chainId: string,
    tx: Uint8Array,
  ): Promise<DeliverTxResponse>;
  getOfflineSigner(chainId: string): Promise<OfflineAminoSigner & OfflineDirectSigner>;
  enabled(): Promise<boolean>;
  install(): Promise<void>;
  getChains(): Promise<Chain[]>;
  deleteChain(chain_id: string): Promise<void>;
  signAndBroadcast(chain_id: string, msgs: Msg[], fees: Fees): Promise<DeliverTxResponse>;
  sign(chain_id: string, msgs: Msg[], fees: Fees): Promise<Int8Array>;
  addAddressToBook(chain_id: string, address: string, name: string): Promise<void>;
  getAddressBook(): Promise<Address[]>;
  deleteAddressFromBook(address: string): Promise<void>;
  getBech32Addresses(): Promise<CosmosAddress[]>;
  getBech32Address(chain_id: string): Promise<CosmosAddress>;
  getAccount(chain_id: string): Promise<AccountData>;
  changeSnapId(snap_id: string): void;
}

Direct Interaction Functions

You can interact with the snap directly to with these functions although we highly suggest using the provider through the window as it is a drop in replacement for other Cosmos wallets.

Check If Installed

import { isSnapInstalled } from '@cosmsnap/snapper';
let result: boolean = await isSnapInstalled();

Check If Initialized

import { isSnapInitialized } from '@cosmsnap/snapper';
let result: boolean = await isSnapInitialized();

Install The Cosmos Extension.

import { installSnap } from '@cosmsnap/snapper';
await installSnap();

Suggest Chain.

Use the format like here in the chain registry. The more info the better.

import { suggestChain } from '@cosmsnap/snapper';
let chain: Chain = {};
await suggestChain(chain);

Get Chains.

Gets all the chains that are in state within the snap.

import { getChains } from '@cosmsnap/snapper';
let chains: []Chain = await getChains();

Delete Chain.

Delete a chain from wallet state.

import { deleteChain } from '@cosmsnap/snapper';
await deleteChain("cosmoshub-4");

Sign & Broadcast.

Sign and broadcast a transaction. Note, you can use our production grade infrastructure (RPCs) to broadcast transactions using this function.

import { signAndBroadcast } from '@cosmsnap/snapper';
import { DeliverTxResponse } from "@cosmjs/stargate";

const msgs = [
    {
        typeUrl: "/cosmos.bank.v1beta1.MsgSend",
        value: {
            fromAddress: senderAddress,
            toAddress: recipientAddress,
            amount: [{
                denom: "uatom",
                amount: "500000"
            }],
        },
    }
];
const fees = {
    amount: [{
        denom: "uatom",
        amount: "500"
    }],
    gas: "200000"
};
let txResult: DeliverTxResponse = await signAndBroadcast("cosmoshub-4", msgs, fees);

Sign Transaction.

Just sign a transaction and return it. Note, this does not use our production grade infrastructure. You must use your own to broadcast the transaction.

import { sign } from '@cosmsnap/snapper';
import { DeliverTxResponse } from "@cosmjs/stargate";

const msgs = [
    {
        typeUrl: "/cosmos.bank.v1beta1.MsgSend",
        value: {
            fromAddress: senderAddress,
            toAddress: recipientAddress,
            amount: [{
                denom: "uatom",
                amount: "500000"
            }],
        },
    }
];
const fees = {
    amount: [{
        denom: "uatom",
        amount: "500"
    }],
    gas: "200000"
};
let txResult: DeliverTxResponse = await sign("cosmoshub-4", msgs, fees);

Add Address to Address Book.

import { addAddressToBook } from '@cosmsnap/snapper';
await addAddressToBook("cosmoshub-4", "cosmos123456789", "John Doe");

Get Address Book

import { getAddressBook } from '@cosmsnap/snapper';
let book: Address[] = await getAddressBook();

Delete Address from Address Book

import { deleteAddressFromBook } from '@cosmsnap/snapper';
await deleteAddressFromBook("cosmos123456789");

Get All Bech32 Addresses

Gets all the Bech32 addresses for all chains in state. Note, this is an expensively heavy operation so use wisely.

import { getBech32Addresses } from '@cosmsnap/snapper';
let allAddresses: CosmosAddress[] = await getBech32Addresses();

Get All Bech32 Addresses

Gets a Bech32 address for a chain.

import { getBech32Addresses } from '@cosmsnap/snapper';
let address: CosmosAddress = await getBech32Address("cosmoshub-4");