Senior Fullstack Software Engineer

1 in 4 people in the US have a treatable mental health condition, but most providers don't accept insurance, making therapy too expensive for most people. Headway’s mission is to fix this by building a new mental healthcare system everyone can access. We started by solving the biggest barrier to care: insurance. The admin work - credentialing, claims, payment reconciliation - is a nightmare. We've automated that. But we're going further. Over 90,000 providers across all 50 states run their practice on our software, serving over 2.6 million patients. We are building the best tools for therapists to run their entire practice, reimagining the experience of finding a therapist, and investing in the platform foundations to enable this at scale, and building much of it with AI. We aren't just a billing layer; we are becoming the platform where care actually happens. We're a Series D company with $325M+ in funding (a16z, Accel, Spark Capital, etc.), looking for exceptional people to help us achieve this mission. We want your time here to be the most meaningful experience of your career. Join us, and help change mental healthcare for the better. The Work Fullstack at Headway means end-to-end ownership. You’re building reliable abstraction layers over a fragmented healthcare system and translating them into seamless, empathetic user experiences. What you could work on: • The Modern AI-enabled Clinical System: Help design and build the interfaces and systems that manage clinical data. Build high-integrity experiences for treatment plans and progress notes, integrating AI-powered clinical intelligence to give providers their time back. • Therapist Practice Management: Build a best-in-class platform for Headway therapists to run their businesses. You'll own features from the database schema to the UI, creating intuitive web experiences for scheduling, clinical notes, and payment management. • Patient-First Experiences: We’re moving toward a patient-centric model. Transform the therapist search experience by building the frontend interfaces and backend APIs that power personalized care recommendations, longitudinal data views, and seamless patient-provider matching. • Frictionless Onboarding: Turn the historically nightmare process of insurance credentialing into a sleek, consumer-grade web experience. Build products and tooling to get providers in-network and scaling their practice in record time. Our Stack • Languages: TypeScript, Python 3 • Frontend: React, Remix, Next.js • Backend & Storage: FastAPI, SQLAlchemy, Postgres, Redis, Snowflake • Infrastructure: AWS, Temporal, Kafka • Ops: Datadog, Sentry, PagerDuty • AI Tools: Cursor, Claude, Gemini, Eddy (our in-house cloud agent harness) Who You Are • End-to-End Product Builder: You care just as much about the API architecture as you do the user experience. You seamlessly context-switch between backend logic and frontend state management. • AI Frontier Tinkerer: You don't just use AI tools - you push their limits. You've experimented with applying LLMs to real workflows, whether that's code generation, operational automation, or developer tooling. You bring a builder's mindset: what can we automate, what should stay human, and how do we ship it responsibly in healthcare? • Owns Outcomes, Not Tasks: You've been handed ambiguous problems and turned them into shipped software. You know how to define the solution, pull in the right people across teams, and keep things moving when priorities shift. • Sets the Technical Standard: You make technical decisions that optimize for maintainability and scale, not just shipping speed. You proactively improve your team's engineering velocity - whether that's refining tooling, improving automation, or establishing patterns that prevent en