Senior Software Engineer II - Flywheel Foundations

Senior Software Engineer II - Flywheel Foundations HubSpot Flywheel Context (Foundations) Team UK - we're open to fully remote, hybrid or office based - whatever works best for you! Role Summary HubSpot is building the next generation of AI-powered experiences across our go-to-market platform. We’re hiring a Senior Software Engineer II to join the Flywheel Context team - a foundational group responsible for building the data and context layer that powers intelligent AI assistants and agents across HubSpot. This is a backend-leaning, data-intensive role focused on building durable production systems. You’ll design and ship the infrastructure that enables AI systems to access relevant customer context, process large volumes of CRM data, and deliver high-quality outputs at scale. If you’re excited about building foundational platforms that unlock smarter AI across an entire product ecosystem, this role is for you. What You’ll Do Design, build, and operate backend services that power context retrieval, enrichment, and insight generation across HubSpot’s platform. Build systems for storing, processing, and retrieving high-volume GTM data (e.g., contact history, CRM activity, behavioral signals). Develop scalable data processing and streaming solutions to support AI-driven use cases. Create reusable platform capabilities and APIs that enable other product teams to build smarter AI assistants and agents. Contribute to evaluation and quality frameworks to ensure context accuracy, reliability, and performance. Collaborate closely with platform teams and downstream product engineering teams to integrate capabilities into real customer experiences. Own end-to-end delivery: architecture, implementation, observability, performance, and iteration in production environments. What We’re Looking For: Strong track record shipping production backend systems as a senior engineer, with ownership from design through operation. Professional experience building maintainable, scalable backend services (Java preferred). Strong data background and experience working with large datasets, data pipelines, and data-intensive systems. Experience building or integrating AI/ML-adjacent systems in production (e.g., retrieval pipelines, embeddings, ranking systems, model-backed services, or similar). Experience operating systems at scale, including performance optimization and reliability considerations. Strong engineering fundamentals: system design, testing, debugging, observability, and operational excellence. Product mindset - comfortable collaborating cross-functionally and building platform capabilities used by other engineering teams. Nice to Have Experience with search, retrieval, ranking, or relevance systems. Familiarity with RAG architectures, vector search, or hybrid retrieval approaches. Experience with streaming technologies or event-driven architectures. Cloud-native development experience (e.g., Kubernetes, AWS/GCP). Some frontend experience or willingness to contribute across the stack when needed. Python experience. Why This Role Matters AI systems are only as good as the context they can access. This team is responsible for unlocking HubSpot’s greatest competitive advantage: the depth and richness of customer data across the platform. Your work will directly impact how intelligent and reliable HubSpot’s AI agents become and enabling a true 360° understanding of customers and accelerate AI innovation across Flywheel.