Mir is an open-source distributed protocol implementation framework designed to facilitate the development, debugging, and analysis of distributed protocols. The framework offers a library with abstractions for various distributed system components and an orchestrating engine ensuring seamless interaction among them. Mir’s architecture is agnostic to network transport, storage, and cryptography implementations, allowing for significant flexibility and customization. Primarily intended as a consensus layer for Filecoin subnets and as a Byzantine fault-tolerant ordering service in Hyperledger Fabric, Mir aspires to serve as a foundational element in next-generation distributed systems. It supports state machine replication and has demonstrated capabilities through implementations of protocols like Alea-BFT. Mir employs a modular design, encouraging developers to implement custom modules while providing several out-of-the-box options. The library emphasizes a robust debugging interface with event recording, inspection, modification, and replay capabilities. Though still in development, Mir invites contributions and collaboration within the open-source community under the Apache License 2.0.