Senior Growth Full-Stack Engineer - Remote US

The Opportunity

We’re looking for a Senior Growth Full-Stack Engineer to join our Activation team at Seamless. This role sits at the intersection of engineering, product, and growth, helping us design, build, and run experiments that accelerate user onboarding, engagement, and activation. You’ll partner closely with growth product managers, designers, and analysts to rapidly ship and iterate on experiments that improve how new users discover value in Seamless.

Responsibilities

• Collaborate with growth, product, and data teams to design and implement A/B tests and growth experiments focused on user activation.
• Build, deploy, and maintain full-stack features and experiment infrastructure (frontend + backend).
• Implement and manage feature flagging systems to enable rapid testing and controlled rollouts.
• Work with GrowthBook (or similar experimentation platforms) to set up, track, and analyze experiments.
• Instrument and track user behavior in Amplitude and other analytics platforms to generate insights.
• Write clean, scalable, and maintainable code across the React frontend and Node.js backend.
• Monitor and evaluate experiment outcomes, providing actionable insights and recommendations.
• Balance speed of experimentation with engineering best practices, ensuring quality while moving quickly.
• The #1 goal of this position is to help Seamless increase user activation, feature adoption, and time-to-value. These efforts will maximize customer retention & satisfaction.

Skillset

• 5+ years of experience as a full-stack engineer (startup or growth-focused environment preferred) with SaaS product.
• Strong proficiency in modern JavaScript/TypeScript (React.js, Node.js)
• Proficiency with modern database technologies (PostgreSQL, Vector DBs, OpenSearch, DynamoDB)
• Proficiency with Cloud architecture and scalability best practices, in particular AWS (Lambda, serverless, cloud-native services).
• Hands-on experience with A/B testing platforms (GrowthBook, Optimizely, LaunchDarkly, etc.).
• Familiarity with feature flag systems and controlled experiment rollout strategies.
• Experience with product analytics tools (Amplitude, Segment, Tableau).
• Ability to translate growth hypotheses into technical experiments quickly and iteratively.
• Strong data-driven mindset with the ability to evaluate experiment outcomes statistically.
• Comfortable working in fast-moving, cross-functional growth teams.

Preferred:

• Background in PLG, growth engineering, activation, or onboarding-focused roles.
• Experience with event-driven architecture and scalable systems.
• Familiarity with in-app education & onboarding tooling (e.g., Userflow).
• Familiarity with Pinecone and LLMs.
• Experience building SaaS applications in the B2B or productivity space.

Education & Requirements

• Bachelor’s degree in Computer Science, Engineering, or a related field (or equivalent practical experience).
• Proven experience delivering full-stack features and experiment infrastructure in a fast-paced environment.
• Demonstrated ability to collaborate across engineering, product, and growth teams.
• Strong problem-solving and analytical skills with a data-first approach.