> For the complete documentation index, see [llms.txt](https://docs.threshold.network/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.threshold.network/app-development/tbtc-sdk/guides/initialize-sdk/ethereum-and-bitcoin-mainnet.md).

# Ethereum and Bitcoin mainnet

This is the most common case when you want to use the SDK to interact with the tBTC bridge on Ethereum and Bitcoin mainnet.

The SDK addresses it by exposing the `TBTC.initializeMainnet` function. That function:

* Takes an Ethers signer or provider as a parameter and uses it to interact with tBTC contracts deployed on Ethereum mainnet
* Automatically configures an Electrum Bitcoin client to communicate with the Bitcoin mainnet (communication is done through a set of pre-configured Electrum servers)

The following code snippet presents the usage of this function:

```typescript
import * as ethers from "ethers"
import { TBTC } from "@keep-network/tbtc-v2.ts"

// Create an Ethers provider. Pass the URL of an Ethereum mainnet node.
// For example, Alchemy or Infura.
const provider = new ethers.providers.JsonRpcProvider("...")
// Create an Ethers signer. Pass the private key and the above provider.
const signer = new ethers.Wallet("...", provider)

// If you want to initialize the SDK just for read-only actions, it is
// enough to pass the provider. 
const sdkReadonly = await TBTC.initializeMainnet(provider)
// If you want to make transactions as well, you have to pass the signer.
const sdk = await TBTC.initializeMainnet(signer)
```

{% hint style="info" %}
The above code snippet presents just one way of creating an Ethers signer/provider. Please refer [Ethers v5 documentation](https://docs.ethers.org/v5/api) to learn more.
{% endhint %}


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