Senior Frontend Developer

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 productMake product and design calls independentlyPrototype and execute designs quicklyEnsure software feels polished with attention to detailImplement and create designs as needed What We're Looking For 4+ years of frontend engineering experiencePortfolio of complex web apps in productionDeep fluency in React and state managementComfortable with full-stack developmentStrong performance instincts and product senseHigh autonomy and low egoUS work authorization or O-1 visa eligibility Nice to Have Experience with multiplayer apps and LLM-based toolsBackground in local-first architecturesDesign background or strong visual senseExperience as a founding frontend engineer Compensation & Benefits Salary: $180,000 – $240,000Meaningful early-stage equityComprehensive health and dental coverage401(k) planConsiderable PTOGym 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 stepsAdd context when something in your background isn't obviousHelp unblock stalled processes or unclear feedbackMake 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.