What the role involves
Founding Applied AI Engineer at Kastle
About Kastle
Kastle is building AI agents for consumer lending starting with mortgage. We work with some of America’s largest mortgage lenders, helping them scale their contact center and compliance operations efficiently using AI-driven voice agents. Backed by $2.3M from Y Combinator, Commerce Ventures, and executives from Snapdocs, Google, and WePay, we are redefining loan servicing with AI.
About the Role
As a Founding Applied AI Engineer, you will play a crucial role in integrating advanced AI technologies into Kastle’s platform. You’ll work on fine-tuning large language models (LLMs), designing AI workflows for highly regulated enterprises, and ensuring our AI agents deliver precise, compliant, and effective interactions.
This role is ideal for an engineer who is passionate about applied AI, eager to solve real-world challenges, and excited to build the technical foundation of an early-stage AI startup.
Responsibilities
AI Model Integration: Fine-tune and deploy LLMs for real-time borrower interactions.
Prompt Engineering: Design, test, and iterate on prompts to optimize AI performance and compliance.
Custom AI Solutions: Train and implement domain-specific AI models for mortgage servicing.
Scalability & Compliance: Ensure AI solutions meet regulatory standards (FDCPA, RESPA, TILA) and scale efficiently.
Data Pipelines & APIs: Build robust AI-driven workflows that integrate seamlessly with loan servicing platforms.
Continuous Optimization: Monitor AI performance, reduce error rates, and enhance borrower experience.
What We’re Looking For
1+ years in applied AI, ML engineering, or a related role.
Proficiency in Python, TensorFlow/PyTorch, and deep learning frameworks.
Experience fine-tuning LLMs (Llama, GPT) and designing AI prompt workflows.
Strong product mindset—ability to bridge AI capabilities with real-world mortgage servicing needs.
Experience with deploying AI models into production and optimizing for speed and accuracy.
Strong communication skills to collaborate with product, engineering, and compliance teams.
Why Join Kastle?
Build and scale AI applications that interface directly with consumers.
Get to interact directly with customers on a daily basis and see them use your work in production and collect feedback.
Work closely with a world-class founding team backed by top investors.
High ownership and autonomy, shaping the company’s technical direction.
Competitive salary, early-stage equity, and frequent company paid site visits to customers.
About Kastle
Kastle is an AI voice agent for mortgage servicing. We help servicers collect payments, verify new borrowers, and qualify new loan inquiries over the phone. Rishi and Nitish met at UIUC where they graduated with degrees in systems engineering and computer science. Rishi was the founding Product Manager for Redfin’s Mortgage Marketplace at 22 and grew the business from $3M to $6M in revenue in 9 months. Nitish patented Verkada’s motion search system and was the youngest tech lead at the company at 23. While building Redfin's Mortgage Marketplace Rishi realized traditional lenders didn't have the infrastructure to service online inquiries and were losing customers. Nitish and Rishi are building Kastle to help traditional financial services companies better interface with their customers.
Full Kastle profile