Backend Engineer (Python) Core API & Agentic AI

HeyMilo is scaling intelligent hiring through AI interview agents that run reliably, in real time, at enterprise volume. Were looking for a mid to senior level Backend Engineer to help own and evolve the core API and backend services that power our platform.

This role is backend-first and product-critical: you'll build scalable Python/FastAPI services, ship new features across the core platform, and keep production stable. Because our main product is an AI interviewer and this team directly owns that orchestration layer, you'll also work hands-on with agent workflows, prompts, and orchestration debugging as part of normal backend development.

What You'll Do

• Build, maintain, and scale Python/FastAPI services that power HeyMilo's core platform and AI interviewer.

• Design and evolve clean, reliable API contracts for product surfaces and internal services.

• Implement backend logic for interview execution, evaluation flows, and real-time decisions.

• Own critical parts of the agentic AI orchestration layer: improve workflows, debug agent behavior, and ensure prompt + tool execution is stable at scale.

• Diagnose and resolve complex production issues across services, async workflows, databases, and external boundaries.

• Improve reliability and performance through strong observability: logging, metrics, tracing, dashboards, alerts, and incident follow-through.

• Refactor and optimize existing systems to improve maintainability, latency, and throughput.

• Work end-to-end: build ship monitor iterate.

Who You Are

• Backend specialist: strong in Python with real production experience building APIs/services.

• FastAPI experience: comfortable designing and implementing scalable endpoints in FastAPI (or similar frameworks).

• MongoDB familiarity: have worked with MongoDB and understand NoSQL/document data modeling (deep expertise not required, but real-world usage is).

• Excellent debugger: a strong debugger who enjoys untangling tricky issues across API boundaries and async workflows.

• Reliability-minded: you care about stability, observability, and performance, and you're comfortable being on the hook for your code in production.

• Agentic AI/LLM curious (or experienced): you're comfortable working with prompts, agent orchestration, hallucination debugging, and tool-calling issues as part of backend ownership.

• Startup-ready: high ownership, independent problem solver, thrive in a fast-paced environment.

Nice to Have

• Experience with async/background job patterns and queues (e.g., Temporal or similar workflow tooling).

• Familiarity with Redis or caching/eventing patterns.

• Experience with DevOps or infra automation in cloud environments.

• Exposure to GCP, Docker, CI/CD pipelines, and micro-service environments.

Standard Requirements

• 3+ years of professional software engineering experience.

• Bachelors degree in Computer Science, Software Engineering, or equivalent practical/CS fundamentals.

• Based in Sri Lanka and open to working remote with a high-ownership, high-velocity team.

Why Join HeyMilo

• Own and scale the backend that powers a rapidly growing AI interview platform.

• Work directly on agentic AI systems in production.

• High agency, high impact: you'll ship meaningful features quickly and see them used at scale.

• Learn fast alongside a strong engineering team with experience from top global tech companies.

• Competitive compensation, performance-driven rewards, and rapid growth opportunities.