# Run an execution client

In order to be able to produce blocks and process incoming validator deposits, you'll need to run an execution client in together with the beacon node.

Nimbus has been tested all major execution clients - see the [execution client comparison](https://ethereum.org/en/developers/docs/nodes-and-clients/#execution-clients) for more information.

The `--web3-url` option informs the beacon node how to connect to the execution client - both `http://` and `ws://` URL:s are supported.

Assuming the execution client is running on the same computer as the beacon node:

```sh
./run-mainnet-beacon-node.sh --web3-url=ws://127.0.0.1:8546
```

> ⚠️ You need to run your own execution client after [the merge](./merge.md) - relying on third-party services such as Infura, Alchemy and Pocket will not be possible.

## Nimbus

In parallel to `nimbus-eth2`, we are working hard on the [Nimbus execution client](https://github.com/status-im/nimbus-eth1). While this is very much a project in development (i.e. not yet ready for public consumption), we welcome you to experiment with it.

## Geth

### 1. Install Geth

See the [Installing Geth](https://geth.ethereum.org/docs/install-and-build/installing-geth) for instructions on installing Geth.

### 2. Start Geth

Once you have geth installed, make sure to enable the JSON-RPC WebSocket interface when running geth:

**Testnet**
```
geth --goerli --ws
```

**Mainnet**
```
geth --ws
```

>**Note:** The `--ws` flag is needed to enable the websocket RPC API. This allows Nimbus to query the eth1 chain using Web3 API calls.


### 3. Leave Geth running

Let it sync - Geth uses snap sync by default. It may take anywhere between a few hours and a couple of days.

>**N.B.** It is safe to run Nimbus and start validating even if Geth hasn't fully synced yet

You'll know Geth has finished syncing, when you start seeing logs that look like the following:

```
INFO [05-29|01:14:53] Imported new chain segment               blocks=1 txs=2   mgas=0.043  elapsed=6.573ms   mgasps=6.606   number=3785437 hash=f72595…c13f23
INFO [05-29|01:15:08] Imported new chain segment               blocks=1 txs=3   mgas=0.067  elapsed=7.639ms   mgasps=8.731   number=3785441 hash=be7e55…a8c1c7
INFO [05-29|01:15:25] Imported new chain segment               blocks=1 txs=21  mgas=1.084  elapsed=33.610ms  mgasps=32.264  number=3785442 hash=fd54be…79b047
INFO [05-29|01:15:42] Imported new chain segment               blocks=1 txs=26  mgas=0.900  elapsed=26.209ms  mgasps=34.335  number=3785443 hash=2504ff…119622
INFO [05-29|01:15:59] Imported new chain segment               blocks=1 txs=12  mgas=1.228  elapsed=22.693ms  mgasps=54.122  number=3785444 hash=951dfe…a2a083
INFO [05-29|01:16:05] Imported new chain segment               blocks=1 txs=3   mgas=0.065  elapsed=5.885ms   mgasps=11.038  number=3785445 hash=553d9e…fc4547
INFO [05-29|01:16:10] Imported new chain segment               blocks=1 txs=0   mgas=0.000  elapsed=5.447ms   mgasps=0.000   number=3785446 hash=5e3e7d…bd4afd
INFO [05-29|01:16:10] Imported new chain segment               blocks=1 txs=1   mgas=0.021  elapsed=7.382ms   mgasps=2.845   number=3785447 hash=39986c…dd2a01
INFO [05-29|01:16:14] Imported new chain segment               blocks=1 txs=11  mgas=1.135  elapsed=22.281ms  mgasps=50.943  number=3785444 hash=277bb9…623d8c
```

Geth accepts connections from the loopback interface (`127.0.0.1`), with default WebSocket port `8546`. This means that your default Web3 provider URL should be: `ws://127.0.0.1:8546`

## Nethermind

See the [Getting started](https://docs.nethermind.io/nethermind/first-steps-with-nethermind/getting-started) guide to set up Nethermind.

Make sure to enable the [JSON-RPC](https://docs.nethermind.io/nethermind/first-steps-with-nethermind/running-nethermind-post-merge#jsonrpc-configuration-module) interface over WebSockets.

## Besu

See the [Besu documentation](https://besu.hyperledger.org/en/stable/) for instructions on setting up Besu.

Make sure to enable the [JSON-RPC](https://besu.hyperledger.org/en/stable/HowTo/Interact/APIs/Using-JSON-RPC-API/) WebSocket interface.

## Erigon

See the [Erigon README](https://github.com/ledgerwatch/erigon#getting-started=) for instructions on setting up Erigon.

Make sure to enable the [JSON-RPC](https://github.com/ledgerwatch/erigon#beacon-chain=) WebSocket interface.