Mid Billing Site Reliability Engineer

Location: Bucharest, Romania

Job Description — SRE Billing

Who are we?

S3NS was created through an industrial partnership between Thales, a global leader in cybersecurity, and Google Cloud, a global leader in cloud solutions. Our ambition is to offer the best of both worlds to organizations concerned with protecting sensitive data, including public institutions, Critical Infrastructure Operators (OIVs), and Essential Service Operators (OSEs). We provide a cloud solution equivalent to Google Cloud Platform (including both GCP IaaS and PaaS services) while meeting the requirements of the SecNumCloud certification.

The Trusted Cloud offering has been generally available in France since October 2025. Google deploys GCP services in a region fully operated by S3NS, including hardware, software, and networking. S3NS has also built a private PaaS hosting S3NS's administrative information system. This consists of all the services required to secure end-customer sensitive data, such as encryption and root-of-trust management, Google source-code inspection, and identity management.

Responsibilities:

This is a hybrid role. The successful candidate will be responsible for operating native Cloud Billing components, including APIs, BigQuery exports, and quotas, within a strict security framework. They will also maintain the internal billing engine that processes raw data to meet the specific requirements of a trusted cloud environment, including re-billing, margins, and sovereignty controls.

Operations & Reliability (SRE)

• Operational Maintenance (MCO): Ensure the availability and performance of billing data export pipelines to BigQuery.
• Billing Observability: Build monitoring and alerting dashboards to identify consumption anomalies, such as cost spikes, and verify the integrity of incoming data.
• Security & Compliance: Ensure that billing data is properly isolated and audited in accordance with trusted-cloud requirements, including encryption and local controls.

Billing Engine Engineering

• Development: Maintain and enhance the internal billing engine that transforms raw Cloud Provider data into "Sovereign" customer invoices.
• FinOps Automation: Develop scripts in Python/Go to automate billing-related functions, such as applying discounts (CUDs), taxes, and specific support fees.
• Data Quality: Design automated data-quality tests to detect discrepancies between actual consumption and billing, such as duplicate records or missing SKUs.

Skills

• Public Cloud: Advanced knowledge of a cloud platform, ideally GCP, and its billing system, including SKUs, pricing models, and credits.
• Data & SQL: Strong SQL skills, particularly BigQuery, for processing large volumes of billing data.
• Development: Ability to code in Go for pipeline automation.
• Infrastructure as Code: Strong Terraform skills for deploying billing-related resources.
• FinOps: Understanding of CUD (Committed Usage Discounts) mechanisms and cloud cost structures.

Personal Skills

• Extreme attention to detail: Billing cannot tolerate approximation, as it has a direct impact on revenue and customer trust.
• Ethics & Discretion: Ability to handle sensitive financial data.
• Intellectual curiosity: Ability to perform deep functional analysis and understand every line item of consumption.
• Ability to synthesize: Ability to translate complex technical data into clear financial reports.

Technical Environment

• Stack: Google Cloud Platform, BigQuery, Grafana, Metabase
• Tools: Terraform, GitHub/GitLab CI, Python, DBT (Data Build Tool)
• Context: SecNumCloud / Sovereignty / High Security / Billing Management

At Thales, we’re committed to fostering a workplace where respect, trust, collaboration, and passion drive everything we do. Here, you’ll feel empowered to bring your best self, thrive in a supportive culture, and love the work you do. Join us, and be part of a team reimagining technology to create solutions that truly make a difference – for a safer, greener, and more inclusive world.

Thales is a global technology leader trusted by governments, institutions, and enterprises to tackle their most demanding challenges. From quantum applications and artificial intelligence to cybersecurity and 6G innovation, our solutions empower critical decisions rooted in human intelligence. Operating at the forefront of defence and security, aerospace and space, cybersecurity and digital identity, we’re driven by a mission to build a future we can all trust.

In Romania, we are advancing innovation through software engineering, research and development, delivering solutions in key markets in which Thales Group operates. Our engineers design, develop and integrate solutions that impact global industries – from fully operational systems and subsystems for naval warfare and maritime security operations, to air traffic management systems, satellite-based solutions, tactical indoor simulations, identity and biometric technologies and more.