Senior Full Stack Engineer

About HumanSignal

Real-world data is the competitive edge in AI.

HumanSignal is a human data partner for companies building AI models and products. Our customers ship better AI, faster, because we partner with their researchers from real-world data creation to annotation to delivery.

We design and create datasets from scratch, recruit and manage the domain experts who evaluate model output, and run everything through our own platform, Label Studio, the open-source standard for data labeling and evaluation, used by over 1 million practitioners worldwide.

We specialize in the operationally complex: real-world data collection, multimodal pipelines, and multi-step workflows. Advanced ML and AI teams use our enterprise platform to run their own data factories, and our services team to extend their reach where in-house capacity runs out.

If you want to do work that materially shapes how the next generation of AI products gets built, we'd love to talk.

About the role

We’re hiring a Senior Full-Stack Engineer with product vision. You’ll build end-to-end features across React/TypeScript and Python/Django, shaping APIs, data models, and background jobs while keeping UIs fast, accessible, and trustworthy. You’ll partner early with PM/Design to frame problems, prototype to learn, and make pragmatic scope calls—so complex, data-heavy workflows feel simple, performant, and reliable.

Responsibilities

• Build full-stack features: React/TypeScript on the client; Django/REST services, data models, and background jobs on the server.
• Own outcomes, not tasks: refine scope, suggest trade-offs, propose simpler approaches, and land increments that deliver value fast.
• Design clean API contracts and evolve schemas/migrations; improve performance and reliability (query tuning, caching, job orchestration).
• Partner with Product & Design from discovery to delivery: clarify user jobs, write lightweight RFCs/PRDs, and shape scope and milestones.
• Keep UIs accessible and responsive; add solid error-handling and failure-mode UX.
• Raise engineering standards: testing strategy, code quality, observability hooks, resilience patterns.
• Partner with Support to investigate production issues, reduce UX papercuts, and turn learnings into fixes.
• 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.

What you’ll bring

• Senior-level experience shipping production full-stack features (React/TypeScript + Python/Django + SQL).
• Strong product sense: you’ve made scope/trade-off decisions and iterated based on real-world usage and feedback.
• Fluency with modern FE tooling (e.g., Vite/Webpack, Jest/Cypress) and state-management patterns.
• Backend depth: REST API design, relational modeling, migrations, performance tuning, and background job patterns.
• Excellent communication at a Senior IC level—you write clear RFCs/PRDs, give actionable reviews, and present trade-offs well.
• Nice to have: GraphQL familiarity; Kafka/queues/streams experience.