Introduction

MUD is a framework for Ethereum applications. It compresses the complexity of building EVM apps with a tightly integrated software stack.

MUD comes with:

1. An on-chain database. No more bespoke data modeling for each app and gas-golfing events.
2. An entry-point framework that brings standardized access-control, upgrades, and modules.
3. Blazing fast development tools based on Foundry
4. Client-side data-stores that magically reflect on-chain state. No need to use view functions and events to get your contract data.
5. A Postgres database you can query with SQL that reflects your on-chain state 1 to 1. Never write an indexer again.

The projects built with MUD speak for themselves: some of the most complex applications on Ethereum have been built with the framework in record time.

OPCraft, a fully on-chain voxel world, was built by Lattice in 1.5 months. While it didn’t have the security and auditing requirement of financial applications, it handled more transaction throughput than most apps on Mainnet ever did in their lifetime: in 10 days, OPCraft players made 3.5 million transactions, filling the MUD on-chain database with billions of gas worth of storage; with the client seamlessly handling synchronizing that state back. OPCraft used MUD without any additional tricks: large on-chain applications with minimal client headaches can be yours too!

MUD is maximally on-chain: the entire application state lives in the EVM, and the only requirement for clients and frontends is an Ethereum Node or a MODE — a MUD node. You can use all MUD libraries together as a framework and get super-powers, or only pick the parts you like. It’s up to you!

<aside> 📢 While there are many Autonomous Worlds (AW) and on-chain gaming projects building on MUD, MUD itself is not specific to AWs and games. Teams have used it for everything ranging from NFTs to ZK projects. We invite you to look at MUD Swap, a port of Uniswap V2 to MUD to explore the benefits of using MUD for an application you might be familiar with.

AWs have historically been at the forefront of on-chain technology: Dark Forest — one of the first AW on Ethereum — famously became the first on-chain application using Zero Knowledge proof, and OPCraft was the first app ever to run on the OP Stack.

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[TODO: diagram/animation of a System, a table definition, a UI screenshot, some UI code, and a Postgres table all working together in sync?]

What’s MUD?

First, let’s clear off common misconceptions:

• MUD is not a rollup or a chain: it’s a set of libraries and tools that work well together to build on-chain applications.
• MUD works on any EVM-compatible chains: Polygon, Arbitrum, Optimism, Gnosis Chain, you name it.
• MUD is gas efficient, it is sometimes cheaper than using vanilla Solidity, and in most cases only ~10% less gas efficient than a hand-optimized version (which would not come with all the MUD features and magic).
• MUD is not just for Autonomous Worlds and on-chain games, although it has been a framework of choice in that community.