Senior Fullstack Engineer

Senior Fullstack Engineer

This role is open to candidates based in LATAM, Africa, and Eastern Europe. Candidates must be available to work during U.S. business hours aligned with the client's time zone.

Our client is a fast-moving marketing measurement and attribution technology company that empowers e-commerce brands to make smarter, data-driven advertising decisions. Their platform combines a robust Rails API, a modern React frontend, and a Python-powered data and ML infrastructure — all operating across a 20+ repository workspace where AI agents and engineers collaborate side by side to ship product y are a team that values engineering craft, architectural clarity, and a bias toward simplicity, and they are looking for senior engineers who raise the bar through code review, documentation, and thoughtful system design as much as through feature delivery.

The Senior Fullstack Engineer will own and elevate engineering quality across a multi-repo platform that spans a Rails API, React frontend, and Python data and ML services. This role sits at the intersection of backend architecture, frontend delivery, and data platform development, making it ideal for a polyglot engineer who is energized by ambiguity and cross-service complexity. The Senior Fullstack Engineer will also mentor fellow engineers, establish best practices, and help design agent-readable systems as AI-assisted development becomes a core part of how the team operates.

Fully Remote (Work from Home) | 9AM - 5PM EST

Key Responsibilities

Backend Development

• Design and ship production features on the Ruby on Rails API (or similar MVc), including authentication flows, background jobs via Sidekiq, and PostgreSQL schema design.
• Maintain and improve API contracts using OpenAPI or JSON:
  
  API standards consumed by SPA frontends.
• Write and enforce test coverage using RSpec, maintaining high reliability across services.

Frontend Development

• Build and maintain React applications using hooks and modern state management patterns.
• Work confidently with Type Script, modern bundlers, and JS tool chains including Bun, Vite, and esbuild.
• Contribute to and evolve a shared component library and design system.

Python & Data Platform

• Contribute to ETL pipelines, Snowflake transformations, and external API integrations.
• Work with orchestration tools such as Dagster or Airflow to manage data workflows in production.
• Partner with Data Science and ML Engineering teams to product ionize models into reliable, observable inference services.

Infrastructure & Dev Ops

• Maintain and improve container-based local development using Docker and Docker Compose.
• Operate within an AWS environment (ECS Fargate, Lambda, Event Bridge, S3) and support infrastructure managed via Terraform.
• Own and improve CI/CD pipelines using Git Hub Actions and drive pragmatic observability across services.

Engineering Leadership & Developer Experience

• Establish and enforce engineering best practices across a 20+ repo workspace, covering testing strategy, CI/CD, observability, and code review standards.
• Improve developer experience through local dev tooling, Makefile automation, and onboarding documentation.
• Lead code reviews and PR triage; drive improvements in type safety, security, and incremental refactoring.
• Write clear specs, RFCs, and architecture docs — including agent-readable context files for AI coding agent workflows using tools like Claude Code or Cursor.
• Mentor engineers through pairing, documentation, and review rather than gatekeeping.

Qualifications — Experience

• 5+ years building production Ruby on Rails APIs (Rails 7+), with deep familiarity with Active Record, Sidekiq, RSpec, JWT/auth flows, and PostgreSQL schema design.
• 5+ years building production React applications using hooks and modern state management patterns.
• Type Script and modern JS tool chains including Bun, Vite, and esbuild.
• Production Python (3.11+) experience, ideally with Dagster, Airflow, or similar orchestration frameworks.
• Hands-on experience contributing to ETL pipelines, Snowflake transformations, and external API integrations.
• Experience with Docker, Docker Compose, and container-based local development workflows.
• Working knowledge of AWS…