Senior Fullstack Engineer, Internal Platform Development

Who is Recruiting from Scratch:

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Title of the Role: Senior Fullstack Engineer, Studio Experience

Location: San Francisco, CA

Company Stage of Funding: Series C AI Infrastructure Company ($10B Valuation)

Office Type: Onsite (5 Days Per Week)

Salary: $130,000–$400,000 + Equity

Company Description

We're representing one of the fastest-growing companies in the AI ecosystem, building the infrastructure that powers the development of frontier AI models. Their platform connects leading AI labs and enterprises with a global network of experts who generate, evaluate, and improve the data used to train advanced AI systems.

As the company continues to scale, they are investing heavily in the internal platforms that support data creation, quality assurance, and delivery for the world's leading AI organizations. This role sits on a high-priority initiative focused on building the systems and user experiences that thousands of contributors, operators, and AI researchers rely on every day to create the data powering next-generation AI models.

What You Will Do

• Own and evolve a mission-critical internal platform used to generate, manage, review, and deliver AI training and evaluation data.

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• Build and maintain full-stack applications spanning contributor-facing workflows, operational tooling, and customer delivery systems.
• Develop scalable React and Next.js applications that support thousands of daily users.
• Design and implement backend APIs, services, workflows, and data pipelines that power core platform functionality.
• Build extensible infrastructure that enables teams to rapidly launch new task formats, workflows, and AI data products.
• Partner closely with Product, Applied AI, Operations, and Engineering teams to translate ambiguous requirements into scalable solutions.
• Drive frontend architecture decisions, component design standards, and engineering best practices across the team.
• Improve performance, reliability, usability, and scalability across complex data-intensive systems.
• Contribute to platform foundations that support future AI evaluation environments, reinforcement learning workflows, and data generation pipelines.
• Help shape the technical direction of one of the company’s most strategically important products.

Ideal Background

• 5+ years of professional full-stack software engineering experience.
• Deep expertise in JavaScript and TypeScript with strong React and Next.js experience.
• Proven track record building and shipping customer-facing or internal production applications at scale.

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• Strong backend development experience with Python and/or Node.js.
• Experience designing relational databases, REST APIs, asynchronous services, and distributed workflows.
• Strong product instincts with a demonstrated focus on usability, user experience, and engineering quality.
• Experience working with high-throughput systems, complex workflows, or large-scale operational platforms.
• Ability to independently lead projects from architecture and design through implementation and deployment.
• Excellent communication skills and ability to collaborate across technical and non-technical teams.

Preferred

• Experience building data labeling, annotation, evaluation, or human-in-the-loop AI platforms.
• Background developing internal developer platforms, workflow engines, or operational tooling.
• Experience with design systems, component libraries, and frontend architecture leadership.
• Exposure to AI products, LLM-powered applications, AI infrastructure, or machine learning workflows.
• Experience working with real-time systems, analytics platforms, or data visualization tools.
• Background at high-growth startups or top-tier technology companies.

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• Experience supporting multi-tenant platforms, large-scale data pipelines, or workflow orchestration systems.
• Strong interest in AI infrastructure and the systems that support frontier model development.

Compensation and Benefits

• Base salary: $130,000–$400,000.
• Generous equity package vested over four years.
• Bi-annual performance bonus structure.
• Up to $15,000 relocation assistance.
• $10,000 proximity bonus for employees living within walking distance of the office.
• $1,500 monthly meal stipend.
• Complimentary Equinox membership.
• Monthly wellness and lifestyle reimbursements.
• Comprehensive medical, dental, and vision coverage.
• Opportunity to work on one of the most critical platforms supporting the development of frontier AI systems.
• Significant ownership, visibility, and impact within a rapidly growing AI company valued at $10 billion.