Senior Backend Software Engineer

Why Cascade? Cascade AI helps HR organizations transform how they operate with AI agents that automate critical HR functions, including support, open enrollment, onboarding, leave of absence, compensation, and more. Our agents execute processes and workflows, streamline HR operations, and deliver employees the help they need instantly and conversationally. By combining LLMs with an organization's existing HR technology stack, Cascade agents streamline operations, improve employee experience, and unlock significant cost savings. Deployed globally across 30+ countries, supporting multilingual workforces. Trusted by dozens of enterprise customers, including Fortune 100 companies. Backed by Gradient Ventures, Google's AI fund. Founded by two former Microsoft engineers through the MIT Sandbox Innovation program. Role: Senior Backend Engineer As a Senior Backend Engineer at Cascade, you will design, build, and own the core backend systems that power AI agents automating real HR work at scale — serving dozens of enterprise customers across 30+ countries, spanning industries from healthcare and energy to SaaS and cybersecurity, with employee populations ranging from 1,000 to 100,000+. This is a high-impact, hands-on role where you'll drive architecture decisions, mentor engineers, and take end-to-end ownership of critical systems — from API design through production reliability. You'll work across APIs, data models, integrations, and LLM orchestration, turning ambiguous product needs into reliable, scalable backend systems. You'll collaborate closely with product, frontend, and customer-facing teams, and you'll be trusted to make high-stakes engineering decisions with minimal oversight. This role is ideal for engineers who combine deep technical skill with strong product intuition, enjoy mentoring others, and want to shape the technical direction of a fast-growing AI company. What Your First Months Could Look Like Own the architecture of a new agent workflow end-to-end. Lead a design review that shapes how we integrate with a Fortune 100 HRIS. Ship an LLM orchestration improvement that measurably increases agent accuracy. Mentor a junior engineer through their first production deployment. What You'll Do Architecture & Systems Design and own the architecture of backend services that power Cascade's AI agent platform, making decisions on system boundaries, data flow, and scalability. Lead technical design for complex features — write design docs, drive architecture reviews, and ensure alignment across teams. Build and evolve APIs that support conversational interactions, task execution, and long-running enterprise workflows. Design data models and storage layers across relational and NoSQL databases (PostgreSQL, Firestore), optimizing for performance and reliability at scale. Own production reliability for your systems — define SLOs, build monitoring and alerting, and lead incident response. AI/LLM Platform Develop and iterate on LLM orchestration logic in Python, including prompt execution, tool calling, state management, and evaluation frameworks. Build ingestion and retrieval pipelines for HR documents and structured data used by AI agents. Design and improve evaluation and testing frameworks to measure and increase agent accuracy and reliability. Enterprise Integration & Security Integrate deeply with enterprise systems such as HRIS platforms (Workday, ADP, UKG), ticketing tools (ServiceNow, Jira), and communication tools (Slack, Microsoft Teams). Implement authentication, authorization, and access controls to meet enterprise security and compliance requirements. Leadership & Collaboration Mentor junior and mid-level engineers through code reviews, pairing, and technical guidance. Identify and drive improvements to engineering processes, tooling, and best practices across the team. Collaborate with product, frontend, and customer teams to shape roadmap priorities and ship end-to-end features. What You'll Need Minimum Qualifications 5-8+ years of professional backend engineering experience in producti