Senior Software Engineer (Core API, Core API - Weights & Biases)

Join Weights & Biases, a leading platform for machine learning experimentation and collaboration. As a Senior Software Engineer, you will be responsible for building and evolving the core backend systems and shared infrastructure that power our platform. You will work on internal schema and code generation tooling, our custom job scheduler, and API standards. This is a high-leverage role focused on durability, scalability, and long-term maintainability. You will collaborate across teams to ensure that shared backend abstractions remain clean, performant, and consistent.

• Conception, développement et amélioration des systèmes backend fondamentaux et de l'infrastructure partagée qui alimentent la plateforme.
• Responsabilité de l'amélioration des outils de génération de schémas internes et de code, garantissant la cohérence et l'exactitude entre les services.
• Collaboration étroite avec les équipes Produit et Ingénierie pour concevoir des systèmes fiables, évolutifs et maintenables dans le temps.
• Experience implementing concurrency and parallelism patterns in production systems
• Experience diagnosing and optimizing system performance, including CPU, memory, I/O, and network bottlenecks
• 5+ years of backend engineering experience building and operating production systems
• Hands-on experience designing and evolving APIs (REST, GraphQL, and/or gRPC)
• Proven experience designing and maintaining distributed systems at scale
• Demonstrated ownership of shared infrastructure, internal platforms, or developer tooling used by multiple teams
• Strong proficiency in Go, Python, or a comparable backend systems language
• Background in high-scale data or ML infrastructure systems
• Experience defining cross-team API standards and governance models
• Experience improving reliability through observability, metrics, and SLO-driven development practices
• We believe in investing in our people and value candidates who bring diverse experiences to our teams — even if you aren’t a 100% match on paper. If you love building foundational systems that other engineers rely on, are curious about distributed execution and performance at scale, and enjoy defining clean and durable abstractions, we’d love to talk
• Familiarity with schema management, code generation tools, or interface definition systems (e.g., protobuf, OpenAPI, GraphQL schemas)
• Experience building or operating custom job schedulers, workflow engines, or execution frameworks