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Senior Fullstack Product Engineer

Pathos

Pathos

Product
San Francisco, CA, USA
Posted on Dec 9, 2025

Location

San Francisco Bay Area

Employment Type

Full time

Location Type

Hybrid

Department

Engineering

Mission

Serve as a full-stack product engineer who owns the end-to-end development of features, from brainstorming and product collaboration to data modeling, pixel-perfect implementation and deployment across backend and frontend. Rapidly deliver high-value, reliable software that delights users and supports the growth of Mentla’s AI Therapist.

Outcomes

  1. Mobile App Launch: Ship a fully functional new mobile app built in TypeScript + React Native, with delightful interactions, beautiful and pixel-perfect design implementation, and deployment to app stores.

  2. Backend: Optimize and scale the TypeScript + Node backend. Add some AI-native features in our Python backend. Design and implement data schemas in Postgres. Deploy code to EC2 using our CI/CD systems.

  3. Own Quality: We’re light on automated testing and code review, and we don’t have an external QA team, so it’s high-trust but quality is your responsibility. Great engineers love this culture, mediocre engineers hate it.

  4. Feature Implementation: Deliver at least 10 major features per quarter.

  5. AI-First: Brainstorm, learn and code using LLMs, to speed yourself up as aggressively as possible. Don’t ship slop, but leverage AI to its full capacity.

  6. Data & Analytics Design: Work proactively with data teams, designing stateful data and analytics schemas in a way that allows us to answer business questions that may arise in the future.

  7. AB Testing: Implement most major features as AB Tests, ensuring statistical accuracy such that results can be reliably trusted and the learnings from each test can accumulate.

  8. Estimation & Communication: Accurately estimate timelines for large projects within ±20% variance. Keep everyone informed. Make sure the train leaves the station on time. Ship.

Competencies

  • Full-Stack: Demonstrates deep expertise in TypeScript, Python, React Native, Node and Postgres, writing clean, efficient code that is highly readable, modular, and optimized for performance. It’s OK to learn lots of details on the job, but should be deeply familiar with most of these technologies.

  • Pixel-Perfect: Translates designs into gorgeous UIs with meticulous attention to detail, ensuring cross-device compatibility and a high bar for UX and UI.

  • Product-Minded: Thinks from the user’s perspective, proactively suggesting user flow improvements and aligning technical decisions with user goals.

  • Fast: Prioritizes speed by leveraging AI, breaking down complex tasks, shipping early, optimizing for learnings, iterating quickly, and avoiding over-engineering.

  • Thinks Ahead: Anticipates future use-cases, especially for stateful parts of the system like analytics and DB schemas.

  • Debugging Expert: Dives into complex bugs with systematic root-cause analysis, ensuring high uptime and preventive fixes. Designs systems to avoid entire classes of bug in the first place.

  • Timeline Estimator: Breaks down projects into granular tasks, accounts for uncertainties, and delivers reliable timelines based on past performance and team dynamics. Provides timely updates on progress to everyone on the team.

  • Quality Obsessive: Refuses to ship subpar work, continuously improving the codebase.