The broader impact/commercial potential of this Small Business Innovation Research (SBIR) project is to use blockchain to facilitate business transactions. Industry analysts estimate there is $3 T of value locked in B2B processes that could benefit from specific types of transactions. This project proposes a new architecture to enable different types of transactions and across blockchain protocols, while maintaining data security, privacy, and other restrictions. This SBIR Phase I project proposes to develop a modular architecture to verify state transfers across different blockchains (including those running different underlying protocols). The research objective is to explore new architectures, including using an interop coordinator based on state commitments submitted by decentralized groups of interop agents. The interop coordinator will then validate their finality according to the consensus specifications of the submitting chain. The interop coordinator will act as the broker for proof requests and responses, as decentralized interop agents from one chain submit requests for proof of a particular transaction in another chain. The prover of the target chain will build a cryptographic proof and forward it to the interop coordinator, to relay the response to the requesting chain. Verification will be conducted by the requesting agent using various methods to be investigated as part of this research. The proposed project approach is distinguished from other interoperability projects in its support for heterogeneous blockchain protocols and the support for arbitrary types of transactions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.