EDR, or Ethereum Development Runtime in full, is a library for creating developer tooling on top of the Ethereum Virtual Machine (EVM), such as an EVM debugger or state inspector. EDR provides a performant API, written in Rust, with bindings for the Node API (TypeScript).
EDR finds its origins in Hardhat but will be a complete rewrite of our Hardhat Network TypeScript code to Rust, incorporating all of the lessons we have learned over the years, and much more to come.