Technical Lead, SWE

About Kastle

Kastle is building the AI employee for banks. We work with some of America's financial institutions, helping them scale their contact center and compliance operations with autonomous AI agents that process payments, originate loans, and guide customers through the biggest financial decisions of their lives.

We've processed over $2 billion in transactions, just raised a $24M Series A, and are backed by Insight Partners and Y Combinator. If you want to build AI that works in the real world, where precision, reliability, and performance matter, and help redefine access to credit, read on.

The Role

As Technical Lead, you'll own the technical direction of the systems behind Kastle's real-time AI voice and compliance agents, and lead the engineers who build them. You'll stay hands-on in the code while setting architecture, raising the engineering bar, and turning ambitious product goals into reliable systems running inside bank environments.

This is a player-coach role: roughly half your time writing and reviewing code, half designing systems, mentoring, and partnering with product, forward-deployed engineering, and customers.

What you'll do

• Set technical direction. Own the architecture of the core platform powering real-time AI voice and compliance workflows, and make the key build-vs-buy and design calls.
• Lead and grow the team. Mentor engineers (this is a player coach role), run design and code reviews, and help hire the next wave of engineers as we scale after our Series A.
• Push performance boundaries. Hold the line on sub-700ms voice latency using event-driven architecture and parallel processing.
• Run reliable systems at scale. Deploy, operate, and scale resilient services on Kubernetes and distributed subsystems, with the observability and on-call practices banks expect.
• Build a self-improving AI system. Design the feedback loops that let our agents get better with every customer interaction and human review.
• Ship fast, ship right. Take projects from whiteboard to live production in bank environments, balancing velocity with security and compliance.
• Partner across the company. Work with product, forward-deployed engineers, and customers to turn real lender workflows into technical roadmaps.

What you bring

• 7+ years building high-performance, real-time backend systems (we work primarily in Python).
• 2+ years leading engineers as a tech lead, staff engineer, or engineering manager, with a track record of shipping large systems through a team.
• Deep understanding of distributed systems, reliability, and fault tolerance.
• Excellent database design and performance optimization skills.
• Hands-on experience running production workloads on Kubernetes and cloud infrastructure.
• Clear written and verbal communication; you can explain trade-offs to engineers, executives, and bank stakeholders alike.
• A bias for ownership and the ability to figure things out in messy, high-velocity environments.

Nice to have

• Experience training, designing, or building production AI/ML systems, especially LLM agents or real-time voice (speech-to-text, text-to-speech, telephony).
• Experience in fintech, banking, or other regulated industries (SOC 2, PCI, data privacy).
• Previous startup or founder experience, ideally scaling a team from early stage through Series A/B.

The interview process

We respect your time. Our process is short and designed to show how you think and lead

• 15-min call with our Talent Lead to learn more about the role
• 1-hour live coding session with a Founding Engineer
• 1-hour system design and technical leadership conversation with the CTO
• 1-day onsite with the team

Why join Kastle

• Work with a world-class team building a generational AI company that will redefine how every loan in America is made and managed.
• Move fast with real impact: add a feature in a few days and ship it to top 10 lenders the next week, reaching millions of customers.
• Shape the engineering org: high ownership and direct input on architecture, team culture, and how engineering scales.
• Competitive compensation plus meaningful equity at a high-growth company.