Senior Software Engineer, Annotations

The Role

We’re looking for a Senior Software Engineer to join our Annotations team and build the systems that power high-quality human data for frontier AI companies. You’ll work at the intersection of product engineering, distributed systems, and AI data operations-designing tools that help operators manage annotation projects, improve task quality, and scale expert workflows.

This is a high-ownership role in a fast-moving environment. You’ll partner closely with product, design, data, operations, and engineering teams to turn ambiguous problems into reliable, intuitive software used across the annotation lifecycle.

What You’ll Do

• Build and scale operator tooling that enables teams to create, manage, prioritize, and audit annotation projects.
• Design workflows and quality-control systems that improve task accuracy, throughput, and customer outcomes.
• Develop performant full-stack features using Node.js/TypeScript, React, PostgreSQL, GraphQL and tRPC..
• Establish technical direction for complex projects, balancing speed, maintainability, reliability, and operational needs.
• Partner with product, design, operations, and data teams to define requirements and ship impactful solutions.
• Lead projects from initial concept through high-quality production delivery, including rollout, monitoring, and iteration.
• Mentor engineers, raise the quality of code reviews and architecture discussions, and help unblock the team.
• Improve engineering processes, testing practices, observability, and operational health across the squad.

You Have

• 6+ years of software engineering experience building and operating production systems.
• Strong proficiency in Node.js, Typescript, React, PostgreSQL, and backend APIs.
• Experience designing scalable, reliable software and making sound architectural tradeoffs.
• A track record of owning complex projects from ambiguity through delivery.
• Strong product judgment and an ability to connect technical decisions to customer and business outcomes.
• Excellent communication skills and the ability to work effectively with technical and non-technical partners.
• A quality mindset: you write maintainable code, test thoughtfully, debug deeply, and address root causes.
• A collaborative leadership style, including experience mentoring engineers and elevating team practices.
• Comfort working in a high-velocity environment where priorities and requirements evolve quickly.

Bonus Points

• Experience building workflow, marketplace, operations, or internal-platform software.
• Familiarity with AI/ML data pipelines, annotation systems, evaluation workflows, or human-in-the-loop products.
• Experience working with distributed teams, expert networks, or high-volume operational processes.
• Contributions to open source or a strong record of self-directed technical projects.

We Offer

Handshake delivers benefits that help you feel supported and thrive at work and in life. Benefits for full-time US employees include:

• Equity in a fast-growing company
• 401(k) match, competitive compensation, and financial coaching
• Medical, dental, and vision coverage
• Mental health support and a $500 wellness stipend
• Paid parental leave, fertility benefits, and parental coaching
• $2,000 annual learning stipend
• Flexible PTO, 15 holidays, and 2 flex days
• Internet, commuting support, and free lunch and gym access in our San Francisco office
• Team outings and referral bonuses