The Stackup bundler is an advanced and versatile bundler, meticulously crafted in Go by the esteemed engineering team at Stackup, with special contributions from Stackup’s co-founder, Hazim (@hazim-j). This bundler adheres strictly to the ERC-4337 standards, ensuring seamless integration with various modules. Developers have the option to self-host this open-source bundler, or they can opt for Stackup’s hosted solution, which provides enhanced convenience and scalability for smart contract wallet developers embarking on their journey.