Joseph McAllister is the Co-Founder and CTO of MouseCat, a Y Combinator-backed (W26) AI platform delivering human-quality fraud investigations at scale for banks, fintechs, and marketplaces.

Joseph studied Computer Science at Cornell University, where he founded Roo Storage, a startup that was acquired in 2020 by Handled (now UniGroup). He went on to build ML and risk infrastructure at Microsoft on Azure Data Factory before joining Coinbase.

Joseph brings rare full-stack expertise spanning streaming data systems, large-scale ML pipelines, and fraud risk modeling, making him uniquely positioned to build the technical backbone of AI-native fraud investigation. His track record of founding, scaling, and exiting a startup before his career at Coinbase signals both entrepreneurial grit and execution ability.

At Coinbase, Joseph spent 4 years building systems that powered every risk decision at the company, focusing on streaming pipelines, large-scale data processing workloads, and improving ACH and ATO risk models. Prior to that, he was a Software Engineer at Microsoft working on Azure Data Factory, a service for Spark-based ETL pipelines.

MouseCat, co-founded with Nicholas Aldridge (ex-AWS AI Principal Engineer), uses AI agents to conduct continuous, post-transaction fraud investigations, integrating with proprietary data and learning from analyst feedback to identify fraud rings and accelerate time-to-mitigation. Backed by Y Combinator and launched in 2026, MouseCat is positioned at the forefront of the AI-driven fraud prevention wave.