Writing your First Nethermind Plugin

Sebastian Dremo
Published in
6 min readNov 25, 2020


We recently added a plugins feature to Nethermind, giving you the ability to extend or modify your local node capabilities. Plugins are easy to build but without proper explaining it can be tricky at some times.

In this post I will explain and show you how to build your first Nethermind plugin.

Types of plugins

  • RPC plugin additional JSON RPC modules to the current pool
  • Block Tree Visitor plugin observe entire block tree and add custom logic on new blocks
  • State Visitor plugin run aggregated analysis on the entire raw format state (or just some accounts storages)
  • Tracer plugin custom EVM tracers capable of extracting elements of EVM execution in real time
  • Cli plugin additional module for Nethermind CLI that can allow you build some quick scratchpad style JavaScript based behaviours

For all of the above plugin types, you can also add custom config to the Nethermind’s config files to further customize your code behaviour in different situations.

Nethermind API

Nethermind Plugins were made possible with introduction of NethethermindApi which was specifically build for simplifying plugin creation. This interface implements four smaller api…