Senior Backend Engineer

About the Role

Join HumanSignal to design and operate scalable Python/Django services powering the next generation of AI data labeling and evaluation workflows. This is a product-engineering role where you will directly shape what we build, ensuring complex processes feel simple, reliable, and fast for leading AI teams.

Responsibilities

• Design, build, and operate robust backend services and APIs using Python/Django, Postgres, and Redis.
• Own outcomes by refining scope, suggesting trade-offs, and safely delivering value increments.
• Model complex data, author migrations, tune SQL queries, and manage high-volume background jobs and queues.
• Evolve clear, versioned, and resilient API contracts in partnership with Frontend teams.
• Enhance system reliability and performance through careful management of timeouts, retries, idempotency, and rate limits.
• Implement secure, multi-tenant patterns including authentication, permissions (RBAC), and auditability.
• Partner with Support to investigate production issues and translate learnings into preventative fixes.
• Engage with the open-source community to understand real-world needs and improve developer experience.

Requirements

• Senior-level experience shipping production backends primarily in Python/Django and SQL (Postgres).
• Strong product sense demonstrated by making effective scope and trade-off decisions based on real-world usage.
• Deep expertise in REST API design, relational data modeling, database migrations, and performance tuning.
• Proven experience managing background processing/queues (e.g., Celery/RQ) and understanding operational concerns.
• Excellent written communication skills for producing concise RFCs/PRDs, actionable code reviews, and clear decision records.

Nice-to-Haves

• Familiarity with GraphQL.
• Experience with streaming technologies like Kafka.
• Exposure to large-scale data processing tools (Spark/BigQuery).
• Background in security/compliance patterns or multi-region architecture design.