Senior Frontend Developer (+ Equity) at AI-native startup backed by YC and Spark Capital

This is a role that TechTree is recruiting for on behalf of one of our clients.

TechTree is an AI-driven recruitment platform working with high-growth companies.

When you apply, our AI Agent matches you not just to this role, but to other relevant opportunities across our network, so one application can unlock multiple roles.

About The Role

We're seeking a Senior Frontend Developer to own the frontend of our core product, Sauna. You'll be responsible for shipping interfaces that are instant, intuitive, and polished, even when the underlying work is complex. This role requires making product and design decisions, prototyping quickly, and executing without perfect specs.

What You'll Be Doing

• Own the frontend development of the core product
• Make product and design calls independently
• Prototype and execute designs quickly
• Ensure software feels polished with attention to detail
• Implement and create designs as needed

What We're Looking For

• 4+ years of frontend engineering experience
• Portfolio of complex web apps in production
• Deep fluency in React and state management
• Comfortable with full-stack development
• Strong performance instincts and product sense
• High autonomy and low ego
• US work authorization or O-1 visa eligibility

Nice to Have

• Experience with multiplayer apps and LLM-based tools
• Background in local-first architectures
• Design background or strong visual sense
• Experience as a founding frontend engineer

Compensation & Benefits

• Salary: $180,000 – $240,000
• Meaningful early-stage equity
• Comprehensive health and dental coverage
• 401(k) plan
• Considerable PTO
• Gym budget and daily lunch

About The Company

Our client is a 12–14 person AI-native team based in San Francisco, building a personal AI assistant for knowledge workers. They've raised $30M in seed funding from Spark Capital, Felicis, and Y Combinator, marking one of the largest seed rounds in YC history. The team consists of former founders, CTOs, and high-agency builders, where high ownership is the norm.

What is TechTree?

TechTree combines AI agents with a human support team to give candidates a better, more transparent hiring experience.

Our AI Agent gets to know your background, experience, and what you're optimising for. It continuously matches you to live roles across our network where there's genuine alignment, not just keyword overlap.

Our Human Team is there to support you through the process:

• Answer questions about roles, process, and next steps
• Add context when something in your background isn't obvious
• Help unblock stalled processes or unclear feedback
• Make sure you're not left guessing, ghosted, or wasting time

We only post real jobs. Every role on TechTree is a live, active hire.

If you apply: you'll be considered for this role, you may also be matched to other relevant roles, and if there's no fit, we won't spam you.