Senior Platform Engineer - Remote (DE, UK, PT, ES)

🌍 About Cozero

Cozero is a carbon accounting platform where enterprises log, calculate, and report their CO2 emissions. Our engineering group is around 12 software and data engineers plus a DevOps Lead, split across two product squads (Insights and Engine) and a Platform squad (Infra, DevOps, Application & DevEx, and Data). We ship in two-week sprints and occasionally stand up tiger teams for the most urgent projects. Platform is the shared foundation the product squads build on, and this role becomes half of its senior technical leadership.

We are open to hiring fully remotely within Germany, United Kingdom, Portugal or Spain.

🖥️ About the Role

We are hiring a Senior Platform Engineer (m/f/d) to become the second senior voice in Platform, alongside our DevOps Lead, and to bridge two worlds he cannot cover alone: application-level developer experience and data engineering.

You will build the automation foundation for the manual data quality checks a single team member has held for years and is now transitioning out of. You keep our analytics layer running while planning its successor. You raise developer experience as a measurable discipline. You are hands-on, you write code daily, and you set the standard for how the engineering group builds and ships.

🎯 What you’ll do:

• Own Application & DevEx in the Platform group. Developer frameworks, application-level tooling, framework upgrades (NestJS, TypeScript ecosystem), test infrastructure, local dev flow, build pipelines. You define "how we build at Cozero" and reduce friction across the engineering group.

• Lead the data platform infrastructure. Warehouse and operational database architecture, cost and performance tuning (Snowflake and Postgres, or similar), orchestration (Dagster, Airflow, or equivalent), ingestion and CDC pipelines, transformation layer, environments and deployment for data workloads, and the infrastructure for AI and ML workloads: serving and inference, LLM application infra, evaluation and versioning, cost control. You work closely with our DevOps lead on the layers underneath. You provide the paved path; Data and Engineering build on top of it.

• Make data reliability an engineering discipline. Pipeline observability, lineage, data quality checks, alerting and freshness SLOs, test coverage for transformations. Convert tribal knowledge and manual checks into maintained, observable, test-covered systems.

• Raise developer experience as a discipline. Build times, test flakiness, local dev flow, repo hygiene, framework upgrade cadence. You measure these and reduce them. AI-assisted tooling (Claude Code, Cursor) is part of the toolkit, and you push the team's fluency here. Eg building skills, agents or Bots to expedite our delivery speed with solid quality gates.

• Participate in the on-call rotation. Every senior engineer, including platform, takes a turn as primary or backup on a 2-week cycle.

• Mentor across squads. Your work touches every squad's daily experience. Fast, actionable code and design reviews.

⭐ You'll thrive in this role if you:

• Have 8+ years of software engineering experience, including 5+ years in a senior IC role owning developer platform, developer experience, or data platform work.

• Have owned developer experience as a first-class product. Build pipelines, test infrastructure, framework upgrades, local dev flow. You have measured DevEx metrics (build time, PR turnaround, flake rate) and moved them.

• Have straddled backend and data engineering deliberately. You are fluent in TypeScript / NestJS and comfortable in Python. You have built ETL pipelines, worked with a warehouse (Snowflake, BigQuery, Redshift, or equivalent), and shipped systems where data correctness matters.

• Go deep on the warehouse and the operational database rather than treating either as a black box. You can reason about Snowflake or similar structures, dynamic tables, warehouse sizing, and query cost, and you have shipped data quality automation: duplicate detection, outlier flagging, schema drift, lineage, whether with dbt tests, a dedicated validation framework, or your own.

• Have shipped data quality automation. Great Expectations, dbt tests, custom frameworks, or your own thing. Duplicate detection, outlier flagging, schema drift, and lineage are all patterns you have implemented.

• Have taken over a system from a single point of failure. You know how to do knowledge transfer well: pair sessions, written runbooks, shadowing, gradual ownership handover.

• Have opinions about test infrastructure at scale. Unit vs integration vs E2E, contract testing, data test fixtures, test parallelisation. You have made these choices in a real codebase and can defend them.

• Are AI-native in your engineering practice. Claude Code, Cursor, or equivalent, integrated into your daily flow. You use AI to move faster on framework work, refactoring, and repetitive automation. You have opinions on where AI helps and where it does not.

• Communicate in writing first. RFCs, tech docs, decision records. Async by default, but you’re not afraid to “pick up the phone” to rapidly unblock yourself, instead of waiting for a fixed meeting.

• Are comfortable with ambiguity. The Application & DevEx charter is broad. You will shape it as much as inherit it.

🙌 Nice to have:

• Experience in climate tech, carbon accounting, or sustainability platforms

• Experience replacing a legacy analytics layer (CubeJS, Looker, Metabase, or equivalent) with a modern stack

• Experience with Prisma ORM at scale

• Experience automating manual data checks into production systems.

• Nx or similar monorepo tooling experience

💚 Why Join Cozero?

• Real technical challenge - You're joining a growing system with real complexity. Work directly reduces carbon emissions at scale. Not theoretical, actual tons of CO2.

• Actual climate impact - Series A funded, growing fast, working with enterprise customers who trust us with their decarbonization journey.

• Exceptional team - Work directly with our founders. And 10+ engineers across Germany, Portugal and the UK. Multicultural, senior-leaning, collaborative, and actually passionate about climate action.

• You'll grow fast - Flat hierarchy. Your ideas ship. Direct impact on product and strategy.

📍 Where You'll Work

Fully remote within Germany, United Kingdom, Portugal or Spain.

🌱 Benefits

• 27 vacation days + 1 day life event leave (Wedding, Birth of child etc.) + national holidays (Depends on location).

• 500 EUR annual learning and development budget.

• 500 EUR one-time home office setup.

• 100 EUR monthly coworking budget (for those outside Berlin headquarters).

• VSOP (Virtual Stock Options) - share in Cozero's success.

• Regular team events every year

We're committed to building diverse teams and creating an inclusive workplace. We welcome applications from all qualified candidates regardless of ethnic origin, gender, religion or belief, age, or sexual identity. Our recruitment process is fair, objective, and based solely on the skills and qualifications required for this role.