The Senior Software Engineer plays a key role in building TransitionZero’s data and modeling platform, which makes energy systems analysis auditable, accessible, and reproducible. This platform is the entry point to all of our data and analysis, including satellite-derived greenhouse gas emissions intelligence, forecast and weather data, and our energy systems modeling capability, accessible through a browser-based interface, APIs, and a Python client library.

As a Python-based developer, you will be responsible for designing, building, and maintaining the core software services that power our flagship model-builder and data-explorer products. You will take a collaborative, team-first approach, helping to raise the bar for the entire engineering team. You will ensure services are observable, operable, production-ready, and well-documented. You are motivated by continuous learning and growth, demonstrating curiosity by asking questions and contributing ideas during company-wide “Neptune” innovation days. Your work will enable TransitionZero to deliver modeling-as-a-service, allowing decision-makers to integrate actionable insights into their workflows and accelerate the global energy transition.

Software Development & Delivery

• Design, implement, and maintain backend services that expose datasets and modeling capabilities through documented, versioned APIs (OpenAPI 3.1).

• Develop and productionise containerised services (Docker, Cloud Build, Cloud Run), orchestrated with Airflow, Dagster, or similar tooling.

• Contribute to architectural and system design decisions, ensuring services are scalable, resilient, and cost-efficient.

• Write clean, maintainable, and well-tested Python code, following CI/CD best practices.

• Develop and use mocks, stubs, and test doubles to enable effective unit and integration testing of services and APIs.

Engineering Excellence

• Ensure APIs and services are robust, well-crafted, documented, and versioned, supporting a Team Topologies “X-as-a-Service” interaction model.

• Champion the adoption of open standards (OpenAPI, AsyncAPI, CloudEvents, OpenTelemetry) for interoperability and transparency.

• Embed observability and operability into services, ensuring monitoring, alerting, and incident response are in place.

• Apply a site reliability engineering (SRE) mindset to ensure services remain performant and reliable under varying workloads.

• Promote a “you build it, you run it” culture, balancing delivery speed with quality and reliability.

• Apply and share software design patterns and best practices, coaching team members on writing clean, maintainable, and extensible code.

• Articulate architecture using appropriate diagrams (e.g., C4 model, sequence diagrams) to ensure shared understanding across teams.

Collaboration & Culture

• Work closely with product owners, energy systems modelers, and analysts to deliver features aligned with user needs.

• Collaborate across teams to integrate new datasets into APIs and modeling products.

• Share technical knowledge through code reviews, documentation, tutorials, and mentoring of junior engineers.

• Maintain accurate, up-to-date documentation and assist with onboarding new engineers to the team.

• Lead or support interviews for engineering candidates, contributing to assessment design and candidate evaluation.

• Provide constructive feedback to peers in code reviews, design discussions, and retrospectives, fostering a culture of learning and improvement.

• Participate in Neptune innovation days, contributing new ideas to TransitionZero’s mission.

• Support Agile ceremonies (stand-ups, planning, retrospectives) and help drive continuous improvement.

• A continuous improver: Reflects on how things can be done better and actively raises the quality, efficiency, and impact of their work.

• Adaptable to change: Comfortable working in a fast-moving environment, open to new approaches, and able to pivot when priorities shift.

• Curious and proactive: Eager to learn, ask questions, and explore new technologies or practices that could improve workflows.

• A collaborative team player: Communicates clearly, shares knowledge, and supports colleagues while fostering a no-blame culture.

• Detail-oriented and reliable: Takes pride in writing clean, well-tested, and well-documented code that others can depend on.

• Mission-driven: Motivated by the opportunity to use technical skills to accelerate the global transition to a zero-emissions economy.

Essential

Experience & Knowledge

• 5+ years of professional software development experience.

• Strong Python development, including scripting and creating libraries.

• Cloud-native development and deployment, including containerisation (Docker, Cloud Run, Kubernetes).

• Building and maintaining APIs with frameworks such as FastAPI or Flask.

• Relational database design, SQL scripting, and database migrations.

• Git-based version control and CI/CD workflows (GitHub Actions preferred).

• Unit, component, and integration testing, with a focus on automation.

• Observability stacks (Prometheus, Grafana, OpenTelemetry).

Skills & Abilities

• Ability to write clean, usable, well-documented, well-tested code.

• Strong collaboration and communication skills; a team player who fosters a no-blame culture.

• Ability to self-organise and contribute to Agile team practices.

• Passion for sustainability and a desire to work in a mission-driven start-up.

Beneficial

• Experience with GCP services (GCS, BigQuery, Cloud Build, Cloud Run, Workflows).

• Developing orchestration pipelines (Airflow, Dagster).

• Infrastructure as Code (Terraform).

• Working with geospatial/Earth observation data (PostGIS, GDAL, GeoPandas, Google Earth Engine).

• Domain-relevant knowledge (energy systems, earth observation, environmental science, climate science).

• Understanding of linear or mixed-integer programming (MILP).

• Post-graduate education (MSc/PhD) in a relevant STEM field.

• Experience with other high-performance or strongly typed languages (e.g., Rust, C++, Java, Go) for performance-critical or optimisation-heavy components.

Studies have shown that some people from marginalised or underrepresented groups are less likely to apply to a role unless they meet all of the hiring guidelines or qualifications. Whoever you are, even if you don't meet all of the criteria, if you can demonstrate a variety of skills and experience relevant to this role, we encourage you to apply as you might just be the candidate we hire! At TransitionZero, we're looking for people who are genuinely passionate about what they do, and we welcome all people, regardless of their background.

If you would like to discuss any reasonable adjustments to the application or hiring process that may better facilitate your participation, please contact our People Team (people@transitionzero.org) for an informal chat. We will make every effort to respond to your request for assistance as soon as possible.