Senior Software Engineer at Fermat

FERMÀT is an AI-native commerce platform that helps brands turn clicks into conversions through dynamic, personalized shopping experiences. As a fast-growing Series B company backed by investors like Bain Capital Ventures and Greylock, we are building the infrastructure for the future of retail and are currently looking for a Senior Software Engineer to join our 70+ person team.

Responsibilities

• Develop and deploy AI products by prototyping, A/B testing, and iterating based on performance, cost, and conversion impact.
• Manage LLM orchestration, including multi-agent systems, function calling, routing, and retrieval strategies.
• Create robust evaluation and observability frameworks to manage prompts, versioning, and system monitoring.
• Build and maintain scalable APIs, services, and caching layers to ensure reliable production performance.
• Integrate first-party event and catalog data while maintaining strict data contracts.
• Develop a vendor strategy by evaluating and integrating various model providers like OpenAI, Anthropic, and Google.
• Mentor team members, lead design reviews, and establish engineering best practices for AI development.

Must-haves

• At least 4 years of professional software engineering experience.
• Proven track record of building and shipping LLM-powered products from prototype to production over the last 12 to 18 months.
• Strong proficiency in Python and TypeScript.
• Deep understanding of LLM APIs, embeddings, vector databases, and agent design.
• Experience with cloud infrastructure, specifically GCP, containers, CI/CD pipelines, and production monitoring.
• Solid foundation in systems design and API development.
• Excellent communication skills and a product-focused mindset.

Nice-to-haves

• Background in e-commerce, recommendation engines, ranking, or advertising.
• Experience with real-time AI interactions using streaming responses, WebSockets, or SSE patterns.
• Familiarity with real-time event pipelines like Kafka or pub/sub systems.
• Front-end development skills in React for rapid prototyping.
• Experience with analytics and experimentation tools such as PostHog.

Benefits

• Medical insurance.
• Dental insurance.
• Vision insurance.
• 401k retirement plan.
• Paid time off.