Mid-Senior Data Engineer (GCP, Python, BigQuery)

B2B SaaS Hybrid - 2-3 days office UK

Location: London

Type: Full-time

We're building the next generation of our data platform for accessible rail travel - powering millions of journeys and enabling new Data-as-a-Service products.

Accessible rail travel depends on systems that work reliably in live environments. Our platform processes large volumes of operational, auditing, and passenger data to generate real-time insights and external data products used by partners and operators.

You'll play a key role in designing and building a modern, cloud-native data platform on Google Cloud: replacing legacy systems and shaping how data is used across the business and by external stakeholders.

Strategic Context

Transreport exists to remove structural barriers in rail travel. Our vision is that everyone has access to travel everywhere.

As a Series A technology company and recipient of a King's Award, we operate across the UK, Japan and the EU, delivering award-winning accessibility and safety platforms that have supported over 10 million assistance requests for more than 1 million users.

As our operational demands grow, our systems must support increasing integrations, regulatory complexity, data volume, and reliability expectations.

Outcomes & Impact

Within 6 months, you will:

Deliver and stabilize our new read-only Data APIs on GCP for external partners, ensuring they meet strict rate limits and utilize cursor-based pagination.

Establish the foundational BigQuery Data Lake using Terraform, deploying automated ingestion pipelines for core platform data.

Assist in the management of the legacy Ruby on Rails auditing applications, ensuring stability while utilizing AI coding assistants to accelerate the migration to the new stack

Within 12 months, you will:

Play a lead role in deploying a new unified Auditing application (FastAPI/Cloud Run), merging internal and external audits into a single cloud-native architecture.

Replace manual Python Jupyter notebooks with fully automated, regulatory periodic reporting engines via Cloud Run and Workflows.

Eliminate legacy database silos by migrating transactional and analytical data into unified Cloud SQL and BigQuery schemas.

• Build & Evolve the Platform: Architect and build serverless Python (FastAPI) microservices on Google Cloud Run to replace legacy monoliths.
• Data Pipelines & ETL: Build and maintain robust ETL/ELT pipelines streaming data from Cloud SQL and external third-party APIs into BigQuery.
• Data Modelling: Write clean, performant SQL to transform raw data in BigQuery into curated, analysis-ready datasets (utilizing tools like Dataform or dbt).
• Data API Ownership: Manage secure, high-throughput external APIs utilizing OAuth 2.0 (M2M) and API Gateway.
• Infrastructure as Code: Utilize Terraform to deploy, secure, and monitor GCP environments.

Must Haves

• 4+ years of professional experience in Data Engineering or Backend Software Engineering.
• Strong proficiency in Python and SQL.
• Hands-on experience with Google Cloud Platform (GCP), specifically BigQuery, Cloud Run, and Cloud SQL.
• Experience building and maintaining ETL/ELT pipelines and transforming data via modelling tools (Dataform, dbt, etc.).
• Experience with Infrastructure as Code (Terraform) and CI/CD pipelines.
• High proficiency in using AI coding assistants to accelerate development and infrastructure tasks.

Nice to Haves:

• Familiarity with FastAPI and asynchronous workers (Cloud Tasks/PubSub).
• Experience with modern BI tools, specifically Looker (LookML) and/or Looker Studio.
• Experience working in regulated industries or multi-client B2B SaaS.
• Comfortable working within legacy codebases (Ruby on Rails) while migrating them to modern architectures.
• Experience designing and scaling REST APIs

• Private healthcare after your probation (including children)
• Company pension scheme
• Hybrid working model
• 25 days holiday
• Volunteering Leave
• Free flu jab for you and your family

Culture & Operating Principles

We value:

• Ownership over hierarchy
• Clarity over bureaucracy
• Impact over job titles
• We operate with high autonomy and high accountability. People are expected to raise risks early, communicate clearly, and take responsibility for outcomes.

Interview Roadmap

• Screening Call (30 mins) - Recruiter alignment
• Technical Exercise - Architecture & integration discussion
• Deep Dive Interview - Engineering & Product
• Final Culture Conversation - Leadership alignment

Guaranteed Interview Scheme

We're a Disability Confident employer and we welcome applications from disabled candidates. If you need any adjustments at any stage of the recruitment process, please tell us what would help - we'll work with you to make the process as accessible as possible.

We also offer a Guaranteed Interview Scheme (GIS) for candidates who consider themselves to have a disability as defined under the Equality Act 2010.

If you indicate this option in your application and your application demonstrates that you meet the essential criteria for the role, you'll be invited to interview or assessment.

Choosing GIS doesn't guarantee a job offer. If you have any questions, please get in touch.