Senior Staff Software Engineer, Search & Recommendation

As a Senior Staff Software Engineer for Search & Recommendation at Cantina Labs, you own search, recommendations, and discovery end to end. Cantina is a social AI platform where users create AI characters and videos, with a catalog growing faster than anyone can browse. Search and recommendations decide which characters new users meet, which creators get discovered, and what appears in every feed and leaderboard. This is the first dedicated hire for this area, so you will inherit a production system serving live traffic and set the technical direction rather than execute someone else's plan.

What you'll do

• Own the architecture and roadmap for search and recommendations end to end, including query understanding, retrieval, ranking, search surfaces, discovery, the home feed, and trending and creator leaderboards.
• Make relevance a measured discipline by defining quality metrics per surface, building offline evaluation and golden-set tooling, and running online experiments that decide whether ranking changes ship.
• Design and evolve the ranking stack, including engagement signal pipelines, decay and freshness models, and the pattern to combine pre-computed index-time signals with live re-ranking at query time.
• Own OpenSearch in production, covering index and mapping design, reindex and cutover safety, query performance, cost, and operational headroom of the clusters behind every discovery surface.
• Build candidate generation and personalization for recommendation surfaces, and partner with data and ML on the feature pipelines and models behind them.
• Work directly with Product and Trust & Safety to define what "good" means for each surface, including quality gates, cold-start behavior for new creators and characters, and what must never be recommended.
• Set the engineering standard for the area through instrumentation, flag-gated rollouts, and runbooks that let other teams change ranking behavior safely.
• Act as the technical point of contact for discovery across backend teams and mentor engineers whose work touches this area.

What you bring

• 10+ years building production software, with substantial depth in search, ranking, recommendations, or ML-driven relevance on a consumer-scale product.
• Hands-on expertise with a production search engine such as OpenSearch, Elasticsearch, Lucene, or Vespa, covering index and analyzer design, relevance tuning, and operating the cluster.
• A rigorous approach to relevance measurement, with ownership of offline evaluation, golden sets, and A/B or interleaving frameworks, and the ability to explain what moved a metric and why.
• Fluency across the recommender stack including candidate generation, feature pipelines, embedding retrieval, and re-ranking, plus a working understanding of serving constraints that can make an offline win fail online.
• Strong distributed systems and backend fundamentals, with production experience in Go or a comparable systems language, and comfort in the data layer behind it such as SQL warehouses and streaming and batch pipelines.
• Demonstrated ownership of an ambiguous area: you have picked up something with no dedicated owner, decided what mattered, and can show the result.
• Clear written communication and the judgment to work with Product on real tradeoffs between relevance, freshness, safety, and latency.

Nice to have

• Experience with AI-generated or rapidly growing content catalogs.
• Experience with severe cold-start conditions or ranking under trust-and-safety constraints.

What we offer

• Annual base salary of $250,000-$320,000 USD, plus generous company equity.
• Medical, dental, and vision insurance with 99.99% of premiums covered by Cantina.
• 42 days of paid time off: 15 PTO days, 10 sick days, 15 company holidays, and 2 floating holidays.
• Generous parental leave and fertility support.
• 401(k) retirement savings plan.
• Lifestyle spending account of $500 per month.
• Complimentary lunch and snacks for in-office employees.
• One Medical membership.

About Cantina Labs

Cantina Labs is a social AI company developing advanced real-time models that power AI character creation and video generation. The Cantina platform lets people create AI characters and the videos those characters star in, transforming how people tell stories, connect, and create.