Cash App provides banking services to millions of customers in the US. The Underwriting and Credit ML Engineering team builds the engineering systems and integrates ML solutions that are responsible for all credit decisions where Block advances funds or provides liquidity to consumers through Cash App and Afterpay. We support millions of customers through products like Cash App Borrow and Afterpay Buy Now Pay Later.

We build automated tools for PCB security verification.

Caspian is an early-stage venture backed startup focused on helping corporations manage their duty and tariff exposure, starting with duty drawback. The team has extensive experience in building enterprise products in the logistics space.

We're building trade software that actually works. Our first product is duty drawback. Every year $10B in potential refunds are left unclaimed. Data is unstructured, fragmented and trapped in legacy systems that don't talk to each other. We're helping companies organize and understand their trade data. Leveraging the wedge product, we intend to quickly grow beyond our initial product.

We're simplifying global trade compliance and helping importers navigate the trade environment, starting with duty drawback—a tax recovery process that puts cash back into importers' hands. Our platform transforms messy trade data into actionable insights, helping businesses recover from the estimated $10B in unclaimed refunds each year.

We’re building an AI-powered home manager: a proactive, chat-first system that helps homeowners stay ahead of bills, maintenance, documents, and expenses. We are backed by founders of Freshly ($1.5B), Kustomer ($1B), and more.

Cassidy is a no-code platform that allows businesses to build custom AI assistants that automate complex multi-step workflows. By connecting to a company’s knowledge (docs, wikis, calls, etc.) and leveraging major AI models, Cassidy aims to be the “AI colleague” for every team—helping them work 100x faster without heavy engineering overhead. We're well funded, growing incredibly fast and have an insane distribution advantage in a growing market.

Castle is a YC-backed Series A startup helping companies like Canva, Atlassian, and Rockstar Games fight fraud and abuse. They are building modern, AI-powered bot detection and abuse prevention tech, with a focus on real-time protection and behavioral intelligence.

Castleton Commodities is an energy fund with engineers in London, New York, and Houston.

Castleton Tower is a boutique consulting firm founded by executives who have built and led quantitative research, data science, and technology teams at top-tier hedge funds and asset managers. We work with investment management firms (asset allocators, asset managers, hedge funds, family offices, and RIAs) helping them modernize their data infrastructure and build AI-ready foundations. We're looking for smart, motivated, high-agency people with similar backgrounds in either data engineering or investing. We have postings up on job boards, but if you email me a resume and 2 sentences you wrote on why you'd be a good fit, I will guarantee it gets looked at.