Senior Backend Engineer

HumanSignal is a human data partner for companies building AI models and products. We are seeking a Senior Backend Engineer with product vision to design and operate services in Python/Django that power labeling and evaluation workflows at scale.

Responsibilities:

• Design, build, and operate backend services/APIs in Python/Django with Postgres/Redis
• Own outcomes, not tasks: refine scope, suggest trade-offs, and land increments that deliver value quickly and safely
• Model data and author migrations; tune queries and caching; manage background jobs/queues for high-volume workflows
• Evolve API contracts with FE; keep interfaces clear, versioned, and resilient to change
• Improve reliability and performance (timeouts, retries, idempotency, rate limits, pagination, backpressure)
• Implement secure, multi-tenant patterns: auth, permissions/RBAC, auditability, and safe data boundaries
• Contribute to testing strategy (unit/integration), error handling, and graceful failure modes
• Partner with Support to investigate production issues and turn learnings into fixes and prevention
• Engage with our open-source community (issues, discussions) to understand real-world needs and improve developer experience
• Participate in architecture discussions and code reviews; mentor teammates and improve patterns across the codebase

Requirements:

• Senior-level experience shipping production backends in Python/Django (or a close equivalent) and SQL
• Strong product sense: you've made scope/trade-off decisions and iterated based on real-world usage and feedback
• Depth in REST API design, relational modeling, migrations, and performance tuning
• Experience with background processing/queues (e.g., Celery/RQ/Kafka-backed workers) and operational concerns
• Clear written communication at a Senior IC level—concise RFCs/PRDs, actionable reviews, and crisp decision records
• GraphQL familiarity
• Kafka/streaming
• Spark/BigQuery
• security/compliance exposure
• multi-region architectures