Product Engineer

About Kastle

Kastle is building AI operating system 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 using AI-driven voice agents. Backed by $2.3M from Y Combinator, Commerce Ventures, and executives from Snapdocs, Google, and WePay, we are redefining lending with AI.

About the Role

You’re joining at an inflection point. As a Product Engineer, you’ll build the playbooks, processes, and relationships that define how Kastle partners with technical customers for long-term success. You’ll be both strategist and hands-on operator.

What You’ll Do

• Be a trusted technical advisor: Guide customers on integrating Kastle into CI/CD and production stacks (APIs, webhooks, auth, SIP/Twilio flows, STT/TTS, LLM configs).

• Drive product feedback: Partner with Engineering; submit crisp RFCs backed by usage data to influence the roadmap.

• Proactive account management: Monitor health, predict risk, and execute save/expansion plays based on telemetry.

• Foundational leadership: Help hire and mentor the future Product & FDE team; set standards as we scale.
  

About You

• Customer-obsessed: You care deeply about measurable outcomes and long-term partnerships.

• Technical pedigree (dev-tool savvy): You can read API docs, inspect payloads, and reason about systems. You’ve used Postman/cURL; you’re comfortable with logs/dashboards and basic scripting.

• Clear communicator: You distill complex concepts for execs and engineers alike.

• Builder’s mindset: You thrive in zero-to-one, create structure from ambiguity, and bias to action.

• Analytical: You ground decisions in data - usage, adoption, performance, and business impact.
  

Minimum Qualifications

• 2 years in a technical role at a developer-focused or infra/SaaS company.

• Comfort with APIs, webhooks, basic SQL, and one of Python/JS (to prototype, parse logs, or write examples).

Nice to Have

• Ex-founder or Early/founding FDE or first FDE hire experience (you built the playbook).

• Familiarity with at least one of: LLM/AI agent tooling, observability/testing

This Might Not Be for You If

• You need rigid processes or heavy structure.

• You prefer pure relationship management without technical depth.

• You don’t enjoy fast-paced, in-person startup environments (we’re in SF, 6 days/week)
  
  

Why join Kastle

Build what banks run on: Your work powers core operations at top-10 lenders—live in production from day one

Act like a founder: High ownership and autonomy with direct input on product, technical direction, and company culture

Learn fast: Daily customer exposure with rapid feedback loops—see your work deployed within days

Strong upside: Competitive salary, meaningful early-stage equity, and relocation support

Great team: Work alongside founders and engineers from Verkada, NVIDIA, Apple, Intuit, and Redfin.