Senior Backend Engineer

Location

Stockholm

Employment Type

Full time

Department

Engineering

About Sana

Sana is an AI lab building superintelligence for work. We believe organizations can accomplish their missions faster when humans can effortlessly access knowledge, automate repetitive work, and learn anything with the help of agentic AI. As part of Workday, we are committed to building AI that augments humans. If that is a mission that excites you, you are in the right place.

About the roles

You will work on the core backend systems that power Sana's Learn platform and search infrastructure. You will redesign and scale systems to handle enterprise workloads, remove deep bottlenecks, and evolve our architecture for the era of AI and agents.

We are hiring for two senior roles:

• Senior Backend Engineer, Learn (Core Systems)

• Senior Backend Engineer, Search

• Senior Backend Engineer, Learn (Core Systems)

About the role

You will focus on making the Learn platform, especially Manage, Insights, and APIs, scalable and maintainable for enterprise use. You will take systems that work at current scale and redesign them to handle much larger volumes of data, users, and entities. The work is primarily architectural and system level, with strong emphasis on Postgres and database design.

In this role, you will

• Redesign existing components to support enterprise scale workloads
• Analyze and resolve bottlenecks in storage, query performance, APIs, and data models
• Lead migrations away from legacy implementations to sustainable replacements
• Improve reliability and efficiency of APIs and integrations for internal and external clients
• Drive technical projects from definition to delivery with Product Managers and other teams
• Maintain a long term view of system health and architecture
• Share technical knowledge, review designs, and set best practices for backend and systems design

What success looks like

• Architecture and scalability are prioritized over short term fixes
• Risks are identified early and addressed with solid technical solutions
• You balance hands on coding with architectural leadership
• Learn core systems support larger enterprise customers without performance or reliability issues

• Strong Postgres skills (schema design, query optimization, indexing) improve performance and scalability

• Senior Backend Engineer, Search

About the role

You will build and scale Sana's search infrastructure for enterprise scale knowledge discovery. You will architect retrieval systems, ranking algorithms, and search APIs that handle large increases in volume while maintaining sub second latency and high relevance. You will rethink the search stack for the era of agents, using engines like Vespa, vector databases, and embedding models.

In this role, you will

• Architect and scale search infrastructure to billions of documents in multi tenant environments
• Design hybrid search that combines keyword search with semantic understanding and vector search
• Build ranking and personalization systems that learn from user behavior
• Collaborate with AI engineers to integrate large language models into the search pipeline and build retrieval augmented systems
• Optimize search performance across query parsing, index design, and distributed architecture
• Lead development of search observability and quality frameworks with clear metrics and monitoring
• Work closely with product and design to shape the future of knowledge discovery at Sana

What success looks like

• Search systems scale elegantly to billions of documents and millions of queries with strict latency targets
• Systems apply proven IR techniques and practical advances in semantic AI retrieval
• Search quality issues are detected early through strong observability and automated regression checks
• You balance implementation with system design and mentor others on search and IR fundamentals
• Deep expertise in search infrastructure (index optimization, query planning, distributed retrieval, caching) prevents performance issues before users see them
• The stack evolves from traditional search to AI powered discovery, including embeddings, reranking, and RAG, while staying reliable
• Search infrastructure supports enterprise deployments with strict SLAs, multi tenancy isolation, and very high uptime

What we offer

• Help shape AI's future alongside brilliant minds from Notion, Dropbox, Slack, Databricks, Google, McKinsey, and BCG.
• Competitive salary and compensation package
• Swift professional growth in an evolving environment, supported by a culture of continuous feedback and mentorship from senior leaders.
• Work with talented teammates across 5+ countries, and collaborate with customers globally
• Regular team gatherings and events (recently in Italy and South Africa)