Senior Software Engineer, Backend Platform

Build a massive, fast-growing business with billions in revenue

About Handshake AI

Human data is the core infrastructure to AI advancement. Frontier AI labs currently improve model capabilities with various data-intensive post-training techniques. We believe that data spend for AI training will increase by 3-5x in the next few years and continue for much longer as models take on new domains. Handshake AI supports all of the frontier AI labs, working on their most complex data at the largest scale.

The Role

Handshake is hiring a Senior Software Engineer to join Backend Platform, with an initial focus on supporting Handshake AI (HAI) and internal AI initiatives.

You will build and maintain backend services, shared platform capabilities, and developer tooling that support HAI and internal AI initiatives. The work centers on core backend platform concerns—service architecture, APIs, data systems, performance, reliability, and developer experience—in an area making increasing use of LLMs and agents.

We are looking for someone who combines strong backend fundamentals with practical knowledge of LLM-powered and agentic systems.

What you'll do

Design, build, and operate backend services and APIs that support HAI products and internal AI initiatives, primarily within our full-stack TypeScript repository.

Develop shared libraries, services, and architectural patterns that reduce duplicated work and make backend systems easier to extend and operate.

Improve the performance, scalability, reliability, and observability of HAI's backend systems.

Lead work involving database design, data access patterns, query performance, indexing, caching, and the evolution of data models as products grow.

Identify recurring product-engineering problems and turn the right ones into reusable platform capabilities and well-understood patterns.

Make sound architectural decisions across mature systems and new services, balancing delivery speed, performance, maintainability, and operational cost.

Contribute directly to internal AI initiatives, including shared capabilities used to build, evaluate, and operate LLM-powered and agentic systems.

Partner with other teams in our Developer Platform group, including ML and Cloud Engineering, on model and service integration, orchestration, evaluation, observability, and failure handling.

Participate in technical planning, design and code reviews, operational support, and incident response.

Mentor other engineers and help establish practical backend engineering standards across HAI and internal AI initiatives.

You Have

5+ years of professional software engineering experience, primarily in backend or platform engineering.

Experience designing, building, and operating production services and APIs.

Strong understanding of distributed systems, data modeling, service boundaries, common backend architecture patterns, and reliability and performance tradeoffs.

We strongly prefer candidates with deep TypeScript and Next.js experience. Because this work is primarily based in a full-stack TypeScript repository, you should be comfortable navigating the broader application and contributing across boundaries when necessary.

Strong experience with relational databases, including schema design, query optimization, indexing, transactions, and diagnosing database-related performance problems. Experience with PostgreSQL is especially relevant.

Familiarity with backend technologies such as Temporal, Redis, Elasticsearch, GraphQL, or event-driven systems.

Experience operating services in cloud and containerized environments. Our broader platform uses technologies including GCP, Kubernetes, Terraform, and Docker.

Practical knowledge of LLM-powered systems, including concepts such as model and tool integration, RAG, agent orchestration, prompt management, evaluation, and observability.

A record of independently driving ambiguous projects from problem definition through production rollout.

Strong communication skills and the ability to collaborate with product engineers and other teams across Developer Platform.

Sound technical judgment and a preference for understandable, maintainable systems over unnecessary complexity.

Bonus points

Direct production experience with product features powered by ML, LLMs, or agents.

Experience with LLM orchestration frameworks or agent architectures involving tool use, memory, and multi-step workflows.

Experience building internal AI tools or shared AI capabilities used by other engineers.

Experience creating internal platforms, paved paths, or self-service tools used by other engineers.

Experience modernizing mature backend systems while continuing to support active product development.

Experience with event-driven architecture or high-throughput data systems.

How we think about this role

This is a backend platform role supporting HAI and internal AI initiatives. The strongest candidates will bring TypeScript and Next.js depth alongside experience in backend architecture, databases, and performance, plus enough practical AI knowledge to contribute directly to this work. Success does not require expertise in every model or framework, but it does require the ability to design and operate the systems around AI-powered product experiences.

We Offer

Handshake delivers benefits that help you feel supported — and thrive at work and in life.

The below benefits are for full-time US employees.

🎯 Ownership: Equity in a fast-growing company

💰 Financial Wellness: 401(k) match, competitive compensation, financial coaching

🍼 Family Support: Paid parental leave, fertility benefits, parental coaching

💝 Wellbeing: Medical, dental, & vision, mental health support, $500 wellness stipend

📚 Growth: $2,000 learning stipend, ongoing development

💻 Remote & Office: Internet, commuting, & free lunch/gym in our SF office

🏝 Time Off: Flexible PTO, 15 holidays + 2 flex days

🤝 Connection: Team outings & referral bonuses

Explore our mission, values, & comprehensive US benefits atjoinhandshake.com/careers.