Founding Full Stack Engineer (Frontend + UX Focus) Job at HartleyCo, Hayward, CA

bmx2a1V4UEpXNWVtM1puWjB1YVhGdVdTL2c9PQ==
  • HartleyCo
  • Hayward, CA

Job Description

Founding Full Stack Engineer (Frontend + UX Focus)

Location: San Francisco (on-site)

We’re helping a YC-backed, seed-stage startup hire a Founding Engineer who can take full ownership of the product’s look, feel, and overall experience. The company builds the simulation and evaluation layer for voice and text AI agents, used by both fast-growing startups and large enterprises.

This role is full stack, but the centre of gravity is very much the frontend. You’ll be the person who makes a complex AI platform feel simple, fast, and genuinely enjoyable to use.

What You’ll Own

  • End-to-end ownership of core UI: dashboards, debugging tools, evaluation workflows.
  • Turning rough ideas into product: sketching, prototyping and shipping quickly.
  • Driving UX quality across the product: layout, interaction, states, polish.
  • Building intuitive interfaces over real-time systems, large datasets, and AI outputs.
  • Dipping into the backend (Python/FastAPI, Supabase, AWS) to unblock yourself and shape APIs.

What They’re Looking For

  • Strong front end engineering with sharp product taste.
  • Someone who cares about clean UI, clear UX flows, and fast interactions.
  • Ability to work full stack when needed, but happiest owning the product surface.
  • Comfortable working on-site with founders, shipping quickly, and iterating with customers.
  • Opinionated about design details and code quality.

Nice-to-Haves

  • Experience with React, TypeScript, Next.js, Tailwind.
  • Exposure to AI/voice tooling a bonus, not required.
  • Prior early-stage or YC/VC-backed startup experience.
  • Examples of beautiful or highly polished UI you’ve built.

If you want to define the visual and interactive identity of a high-velocity AI product and sit at the heart of a tiny founding team, this is the one.

Job Tags

Similar Jobs

Nicklaus Children's Health System

Child Life Specialist Job at Nicklaus Children's Health System

 ...assessments of psychosocial needs of patients and families within 24 hours of consult. Serves as backup preceptor for practicum students and intern students once hours set by the Association of Child Life Professionals and competencies are met. Serves as unit... 

St. Catherine University

Program Director-Master of Library and Information Science Job at St. Catherine University

 ...Program Director-Master of Library and Information Science Division: Academic Affairs Department/Office: MA Library Info Science...  ...planning and future visioning in a changing higher education environment and in alignment with institutional strategic priorities... 

Confidential

IT Project Manager Job at Confidential

 ...non-technical stakeholders. Project Management: Experience managing medium-to-large-scale IT projects from planning to completion; PMP certification is a plus. Certifications: Relevant certifications such as Microsoft MCSE/MCITP, VMware VCP, CompTIA Network+... 

Heritage Health Network

RN Care Manager (Bilingual) Job at Heritage Health Network

 ...social service partners. Collaboration occurs daily to support assessments, care planning, escalations, transitions of care, and member outcomes...  ...to NP/MD partners; provide brief interventions within RN scope as needed. Participate in interdisciplinary Systematic... 

Daltile

Warehouse Supervisor Job at Daltile

Job Objective: The Supervisor Distribution is an entry-level leader who is responsible for supervising, coordinating, and directing the day-to-day operational activities of their designated distribution center. This role is responsible for training and developing hourly...