Skip to content

Run an execution client

In order to perform validation duties, you need to also be running an execution client - at least one for each beacon node.

Nimbus has been tested all major execution clients - see the execution client comparison for more information.


You need to run your own execution client - relying on third-party services such as Infura, Alchemy and Pocket is no longer possible. Sharing the same execution client between multiple beacon nodes is not supported.


Syncing an execution client may take hours or even days, depending on your hardware! The backup providers will be synced only when the primary becomes unavailable, which may lead to a small gap in validation duties - this limitation may be lifted in future versions.


1. Install execution client

Select an execution client and install it, configuring it such that that the authenticated JSON-RPC interface is enabled and a JWT secret file is created.

In parallel to nimbus-eth2, we are working hard on the Nimbus execution client. While this is very much a project in development (i.e. not yet ready for public consumption), we welcome you to experiment with it.

1. Install Geth

See the 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, along with the options for creating an autheticated RPC endpoint:

geth --authrpc.addr localhost --authrpc.port 8551 --authrpc.vhosts localhost --authrpc.jwtsecret /tmp/jwtsecret
geth --goerli --authrpc.addr localhost --authrpc.port 8551 --authrpc.vhosts localhost --authrpc.jwtsecret /tmp/jwtsecret

3. Leave Geth running

Let it syns - it may take anywhere between a few hours and a couple of days.

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

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 localhost interface (, with default authenticated RPC port 8551. This means that your default Web3 provider URL should be:

See the Getting started guide to set up Nethermind.

Make sure to enable the JSON-RPC interface and pass --JsonRpc.JwtSecretFile=/tmp/jwtsecret to select a JWT secret file location.

See the Besu documentation for instructions on setting up Besu.

Make sure to enable the JSON-RPC interface and store the JWT token in /tmp/jwtsecret.

See the Erigon README for instructions on setting up Erigon.

Make sure to enable the JSON-RPC interface and use --authrpc.jwtsecret=/tmp/jwtsecret to set a path to the JWT token file.

2. Leave the execution client running

The execution client needs to be running at all times in order for the beacon node to be able to support validators. It will start its syncing process as soon as the beacon node connects to it - once both are synced, they will continue to work in tandem to validate the latest Ethereum state.

It is safe to start the beacon node even if the execution client is not yet fully synced and vice versa.

3. Pass the URL and JWT secret to Nimbus

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

Once started, the execution client will create a file containing a JWT secret token. The token file is needed for Nimbus to authenticate itself with the execution client and perform trusted operations. You will need to pass the path to the token file to Nimbus together with the web3 URL.

./ \
  --web3-url= \
./ \
  --web3-url= \

Multiple execution clients

You can pass one or more --web3-url parameters to the node as long as they share JWT secret. Any additional web3 URLs will be used for backup, should the first one become unavailable:

./ \
  --web3-url= \
  --web3-url=ws://other:8551 \