SWEEP
Senior Fullstack Engineer (Freelance)
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Senior Fullstack Engineer (Freelance) – Sustainability Data Intelligence
Sweep is looking for a Senior Fullstack Engineer to work on our Sustainability Data Intelligence Platform.
Climate change is the defining issue of our time. Sweep builds a sustainability data intelligence platform used by major enterprises to track greenhouse gas emissions, meet regulatory requirements, and drive real decarbonization. We're a B Corporation, and we mean it.
About the Role
As a Senior Fullstack Engineer, you’ll own features end-to-end, from data models and backend systems to interfaces that make sustainability data actionable. You’ll work at the heart of our core product, alongside a team that cares deeply about quality and impact.
What You’ll Be Working On
Core Responsibilities
- Build and own core product features:
- Design and implement full-stack features from the ground up: database schema, backend logic, GraphQL API, and React/TypeScript UI
- Take full ownership of significant parts of the system, driving reliability, performance, and long-term maintainability
- Participate in every stage of the development lifecycle—from design & implementation to rollout & production operation
- Contribute to and challenge our technical architecture as we scale
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Backend Mastery
- Bring genuine backend depth:
- Design robust data models & schemas built to perform at scale
- Build and operate backend services, including background jobs, async pipelines, and integrations with third-party systems
- Own observability: instrument systems, define meaningful metrics, and respond to incidents with confidence
- Identify and address security risks proactively—IPD APIs to infrastructure exposure
- Automate deployments via our CI/CD systems and continuously improve development processes
AI-Integrated Development
- Work with AI as a daily accelerator:
- Leverage AI tools in your workflow—code generation, review, debugging, and documentation—delivering faster without sacrificing quality
- Contribute to AI-assisted development practices across the engineering team
- Stay curious about emerging AI capabilities and drive innovations for better, faster shipments
Team Multiplier & Quality Champion
- Be a team force multiplier:
- Lead technical design on major features and share your expertise openly
- Review pull requests with rigour and care, setting a high standard for the whole team
- Participate actively in team rituals (stand-ups, planning, retrospectives)
- Foster a culture of quality—ensure changes are incremental, well-tested, and observable
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- Pursue excellence always:
- Champion clean code, strong test coverage, and rigorous engineering practices
- Improve processes and methodologies to meet the highest standards
- Bring excellence to your work and help others do the same
What You’ll Need to Bring
- 5+ years of experience shipping product across the full stack, with strong backend foundations
- Fluent in React/TypeScript for frontend; deep expertise in:
- Relational databases
- Distributed systems
- Observability
- Security
- Comfortable with owning features end-to-end, requiring autonomy and clear communication
- Strong plus: Experience with Ruby on Rails in a high-scale production environment
- Prides yourself on writing clean, well-tested code and taking genuine ownership of work
Practical Details
- Location: Hybrid or Remote (offices in Paris, London, Montpellier, Denver)
- Start Date: ASAP
- Duration: Long-term collaboration, renewable
- Rate: 520€ per day
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