Fullstack Engineer, Seller Growth

Whatnot · Consumer · San Francisco, CA · Engineering

Fullstack Engineer role focused on seller growth, involving building systems for fraud detection, identity verification, seller enrichment pipelines, and A/B testing. The role also involves creating scalable data pipelines and growth systems. While not directly building core AI models, the role leverages and builds systems that incorporate predictive models and signals for seller routing and risk assessment, indicating an AI-adjacent function within a consumer marketplace.

What you'd actually do

  1. Protecting the funnel from fraud and abuse: Developing and scaling systems for identity verification (IDV), fraud detection, and automated trust/risk reviews that safeguard buyers while minimizing friction for good sellers.
  2. Ship seller-facing experiences: Deliver features across onboarding, education, and seller incentive flows — working across the full stack (backend and frontend).
  3. Build platform intelligence: Develop seller enrichment pipelines and signals to route sellers to the right onboarding, incentive, and discovery paths.
  4. Drive growth through experimentation: Design and analyze A/B tests to guide product decisions and accelerate seller success.
  5. Create scalable infrastructure: Build and maintain data pipelines and growth systems (e.g., notifications, lifecycle triggers) that other pods and teams can leverage.

Skills

Required

  • 3+ years of generalist software development experience in high growth startups
  • Bachelor’s degree in Computer Science, a related field, or equivalent work experience
  • Knowledge of multiple programming languages (Python, Elixir, JavaScript preferred)
  • Web development experience with React
  • GraphQL for API development
  • Modern frontend applications
  • Excellent product instincts
  • Mentorship ability
  • Strong ownership instincts
  • Ability to ship products and features quickly
  • Excellent problem solver
  • Ability to operate autonomously
  • Ability to pick up on new technologies very quickly
  • Proven track record of delivering features

Nice to have

  • exposure to Next.js framework

What the JD emphasized

  • deeply technical systems (IDV, fraud signal repositories, seller enrichment pipelines, predictive models)
  • scale this influx without compromising marketplace integrity
  • Proven track record of delivering features

Other signals

  • Develop seller enrichment pipelines and signals to route sellers to the right onboarding, incentive, and discovery paths.
  • Develop and scaling systems for identity verification (IDV), fraud detection, and automated trust/risk reviews that safeguard buyers while minimizing friction for good sellers.
  • Build and maintain data pipelines and growth systems (e.g., notifications, lifecycle triggers) that other pods and teams can leverage.