Senior Fullstack Engineer (Backend Focus)

We’re looking for a Senior Full Stack Engineer to help build the AI-driven products at the core of our platform. You’ll work directly with our proprietary dataset - real-time, anonymized cross-brand transaction data - to build the services, agents, and tools that power Conversion Intelligence.

This is a full stack role with a center of gravity in the backend. The majority of your work will be backend services, data systems, AI orchestration, and APIs - but you’ll also own the UIs that surface this work to users, so you should be genuinely comfortable across the stack. If you thrive in fast-moving environments and are energized by pushing the limits of AI-assisted development, we’d love to talk.

What You’ll Own

• Design, build, and document backend services and APIs that power our AI-driven products
• Develop end-to-end features across AI agent interfaces, orchestration layers, and developer-facing tools
• Query, model, and manage relational databases - own the data layer, not just consume it
• Build and scale the systems that turn cross-brand transaction data into product
• Ship responsive, clean UIs in TypeScript and React where the product needs them
• Own projects from architecture to deployment in an agile, high-velocity environment
• Collaborate cross-functionally to ship high-impact features quickly
• Stay current on modern AI development practices and tooling

Do you have experience in UI implementation?, * 6+ years of professional software development experience

• Strong backend proficiency in TypeScript, with solid working knowledge of SQL and relational database design
• Demonstrated experience building or integrating AI-powered applications - agents, orchestration, or LLM-backed systems
• Proven track record in startup environments - you’ve shipped fast and worn multiple hats
• Comfortable owning projects independently in high-velocity environments
• Working proficiency in React and the ability to build production UIs when the work calls for it
• Daily use of AI-assisted coding tools (Cursor, GitHub Copilot, Claude Code, etc.) - this is a requirement, not a nice-to-have
• Bachelor’s degree or higher in Computer Science, Engineering, or a related field

Nice to Have

• Proficiency in Python
• Experience with AI agent frameworks, orchestration tools, or embeddings
• Background in data engineering (ETL, dbt, Airflow, etc.)
• Familiarity with cloud platforms (AWS, GCP, Azure) and containerization (Docker, Kubernetes)
• Experience writing production-grade CSS/SCSS

Pulled from the full job description

• Paid parental leave
• Parental leave
• 401(k)
• Health insurance
• Vision insurance
• Health savings account
• Dental insurance, Why Proxima
• Work on one of the most differentiated data assets in consumer tech
• High ownership and accountability - drive projects end-to-end and make decisions that actually matter
• Lean team where your contributions are visible and your voice carries weight
• Highly cross-functional - work closely with product, data, growth, and leadership
• Hybrid setup in our NYC office with a collaborative in-person culture, plus quarterly team events in and out of the office

Benefits & Perks

• Competitive base salary and meaningful equity
• Comprehensive medical, dental, and vision coverage
• HSA and FSA options
• 401(k)
• 12 weeks of fully paid parental leave
• Unlimited PTO
• Summer Fridays from July 4th through Labor Day
• Mental health and wellness support through Talkspace, Health Advocate, and One Medical
• Commuter benefits
• $1,000 annual learning & development stipend
• Quarterly team events, both in and out of the office, Compensation Range: $150K - $190K

Proxima is the Conversion Intelligence platform for ecommerce. Powered by a proprietary Commerce Graph spanning 73M+ buyers across 2,000+ ecommerce brands, we help teams understand what actually drives conversion across the broader market, and turn those signals into clear creative direction.

Our data is deterministic (real names, emails, and addresses from actual orders, not inferred from sessions), granular (full SKU-level receipt data), and point-in-time (timestamped history that enables recency scoring and ML without look-ahead bias). Headquartered in New York City, we’re a team of operators, builders, and ecommerce veterans solving the hardest problems in modern customer acquisition.