End Close

Sean Bolton was the third hire at Modern Treasury (YC S18). He spent 6 years there, first as tech lead of payments engineering, then building and running the entire reconciliation org from the ground up. Under his leadership, Modern Treasury scaled to $350B in annual payments volume and $1T in annual reconciliation volume with 99.995% automation across 40 banks. He literally built the product category he is now turning into a standalone company. Holds a Master's in Entrepreneurship from the University of Notre Dame (ESTEEM program). Previously worked at Bricleir and GAAStrength.ie. X: @SeanBolton. David Newell is the CTO - this is his third time through YC. He co-founded Unflow (YC S19), a no-code mobile experience platform, where he served as CTO. After that, he joined PostHog (YC W20) as a product engineer and led the error tracking product, which became the fastest-growing product in PostHog's history. Before all of that, he interned at Basecamp (the company that literally wrote the book on remote work) and worked as a product engineer at Intercom, where he was part of the first use-case team. His GitHub location lists Galway, Ireland. He attended Coláiste na Coiribe in Ireland and was founder of Student Startup Dublin. X: @DavidNewell95. GitHub: github.com/daibhin. For Backend/Infrastructure Engineer: Build a mini proof-of-concept that demonstrates reconciliation logic. Take two mock data sources (say, a CSV of Stripe payouts and a CSV of bank transactions), write a matching engine that identifies exceptions, and present the unmatched items with context. Deploy it as an API. Send it to Sean. Reference his Modern Treasury background directly. Your cold email angle: 'Saw you spent 6 years building the reconciliation org at Modern Treasury from the ground up. That experience at a $2B payments infrastructure company is exactly the kind of context that makes End Close credible from day one. I built a small reconciliation matching engine to show how I think about the problem.' Keep it tight. Sean spent years with engineers who understand payments deeply. Show him you are one of them. For Full-Stack Engineer: Build a mock exceptions inbox. Show a dashboard with transactions, match statuses, an AI-suggested resolution panel, and an audit trail. Use the design language from their existing website (clean, dark mode, developer-focused). Send it to David. Reference his PostHog and Intercom product engineering background. He built products used by millions. Show him you think about developer experience the same way. For AI/ML Engineer: Build a prototype exception-resolution agent. Feed it a payment discrepancy (mismatched amounts, duplicate charges, timing issues between processor and bank), have it gather relevant context from mock data sources, and output a structured resolution recommendation with confidence scoring. Show it working end-to-end. This maps directly to the core AI agent in the product.