Software Engineer - Intern

Kastle is building an AI operating system for consumer lending, starting with mortgage, and works with America's largest mortgage lenders to scale contact center and compliance operations using AI-driven voice agents.

About Kastle

Kastle is building the AI employee for consumer lending. We work with some of America's largest banks and mortgage lenders, helping them scale their contact center and compliance operations using autonomous AI Agents that process payments, originate loans, and help customers get a world-class experience during the biggest financial decisions of their lives. We've processed over $1 billion in transactions and are backed by Y Combinator and Commerce Ventures.

About The Role

We're looking for a Software Engineer Intern who is excited to build products that are used by millions of users every month. As an intern, you won't spend your summer fixing minor bugs or working on isolated projects—you'll work alongside experienced engineers to design, build, and ship production software and AI Agents that are deployed at some of the world’s largest banks. You'll join a small, fast-moving team where you'll have real ownership, receive frequent feedback, and learn how software is built from idea to deployment. If you're curious, enjoy solving difficult problems, and want to grow as an engineer by building meaningful products, we'd love to meet you.

Responsibilities

• Ship agent capabilities that run in production at national banks and servicers
• Contribute to evals and QA harnesses that catch failure modes and make reliable AI scale in production
• Work with the latest voice and language models — latency, interruption handling, grounding, tool use — and integrate them into enterprise environments
• Sit in on real customer calls and learn directly from executives about how AI gets deployed in the real world
• Contribute to technical documentation and internal tooling

Requirements

• Currently pursuing or recently completed a Bachelor's / Master's / Bootcamp degree in Computer Science, Software Engineering, or a related field
• Strong programming fundamentals in at least one language such as Python, Java, Go, JavaScript, TypeScript, or C++
• Experience building personal projects, coursework, hackathon projects, or previous internships
• Familiarity with web development, APIs, databases, or cloud platforms is a plus
• Strong problem-solving skills and attention to detail
• Comfortable working in a collaborative, fast-paced environment
• Eager to learn, ask questions, and continuously improve

Skills

• Experience building agents that operate in real-time settings (bonus)
• Interest in consumer lending, banking, or financial services (bonus)

Benefits

• A rare opportunity to contribute to a company that will redefine an entire industry
• Hands-on experience building software used by real customers
• Mentorship from experienced engineers
• Exposure to the full software development lifecycle—from planning to production
• Opportunities to own meaningful projects and present your work
• A collaborative team environment focused on learning, growth, and impact