Contract Frontend Developer Jobs in California (NOW HIRING)

Handshake was founded on a simple belief that everyone deserves a path to a great career, regardless of where they went to school or who they know. Today, we power 25 million job seekers, 1 million+ employers, and 1,600 educational institutions.

In 2025, we started Handshake AI and built the fastest-growing AI data business in history. We work directly with frontier AI lab researchers to create evaluations, publish benchmarks, and push the boundary of data. We’ve grown from $0 to ~$1B run rate and pay ~$60M to over 30K individuals every month.

Why join Handshake now:

• Shape how every career evolves in the AI economy, at global scale, with impact your friends, family and peers can see and feel

• Partner hand-in-hand with world-class AI labs, Fortune 500 partners and the world’s top educational institutions

• Work together with engineers, scientists, operators, and more from Palantir, Meta, Scale AI, and former YC founders

• 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.

Handshake AI Enterprise is a new business unit building AI-powered applications for the world's largest companies. We deploy small, expert teams directly into enterprise environments — deeply learning each customer's business, defining where AI can drive real impact, and building and iterating on agents that automate their most critical workflows. We're not a consulting firm and we're not selling software. We're building and deploying AI that measurably changes how enterprises operate.

We're looking for a Senior Frontend Engineer who wants to architect the foundation — not just build on top of it.

As our first senior frontend hire, you'll define how we build UI across the entire team. That means establishing the component system, design language, and engineering patterns that every engineer who comes after you will rely on. You'll set the technical bar, make the foundational decisions, and build in a way that scales — so others can move fast without sacrificing quality.

This is a rare opportunity to own the frontend architecture of a new product from zero, at a company with the data, lab relationships, and momentum to win.

Location: San Francisco, CA | 5 days/week in-office

• Architect the frontend foundation for Handshake AI Enterprise — component system, design tokens, patterns, and engineering conventions that the whole team builds on

• Make foundational technology decisions: framework choices, state management, rendering strategy, performance budgets

• Build shared libraries and abstractions that let other engineers move fast without reinventing the wheel or sacrificing quality

• Establish code standards, review practices, and documentation that scale as the team grows

• Collaborate closely with Applied AI and Platform engineers to define clean API contracts and integration patterns

• Ship production-grade UI for enterprise customer deployments alongside building the foundation

• Evolve the architecture over time as the team, product, and customer base scales

• 5–6+ years of frontend engineering experience with a strong architectural track record

• Deep expertise in ReactJS and TypeScript — you understand the tradeoffs, not just the syntax

• Proven experience building and maintaining shared component libraries or design systems used by other engineers

• Strong opinions on frontend architecture — state management, rendering patterns, performance, accessibility — and the ability to defend and evolve them

• Experience making technology decisions that others depend on, with an eye toward long-term maintainability

• Comfort working in ambiguous, fast-moving environments where the right answer isn't always obvious

• Strong communication skills — you'll need to align engineers, product, and design on how things get built

• Experience building frontend architecture for AI-powered or data-intensive applications

• Background at a company known for high craft — you've seen what a great design system looks like from the inside

• History of writing technical documentation or guides that helped other engineers ramp quickly

• Experience with performance optimization, accessibility standards, or cross-platform rendering at scale

• Familiarity with enterprise deployment environments or security constraints

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, and vision, mental health support, $500 wellness stipend

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

💻 Remote & Office: Internet, commuting, and 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, and comprehensive US benefits at joinhandshake.com/careers.

Compensation Range: $205K - $300K