Senior Engineer (m/w/d)

The client is looking for a highly experienced freelance hands-on Tech Lead / Senior Engineer / Architect to deeply assess the technical state of our e-commerce platform and actively support the team in driving a critical technical overhaul. The platform currently suffers from significant architectural and technical debt, especially in the area of payment and billing, which severely impacts maintainability, scalability, and development speed. Your expertise will be crucial in helping the client regain technical reliability and chart the best course forward - whether through overhaul, rebuild, or other strategies.

Responsibilities:

* Conduct a deep-dive technical assessment of the e-commerce platform’s architecture, codebase, infrastructure, and critical modules (e.g., payment and billing).
* Identify root causes of technical debt, bottlenecks, and architectural risks.
* Provide clear, actionable recommendations for the technical overhaul, including potential roadmap adjustments, priorities, and risk mitigation.
* Act as a technical sparring partner for the Platform Lead, advising on key decisions regarding technical direction and team setup.
* Support the team hands-on: guide and unblock developers where needed, review code, and help implement critical fixes.
* Establish or improve standards and practices for code quality, testing, observability (monitoring, logging, alerting), and CI/CD pipelines.
*Help define and validate the scope of required work (e.g., tech overhaul vs. rebuild) and the associated resource needs.
* Optionally, assist in identifying longer-term technical leadership or agency solutions.

You’ll work in a modern, cloud-native JavaScript environment with:

* Frontend: Remix, ReactJS with TypeScript, Shadcn, Storybook, Vite
* Backend: NestJS and Node.js
* Testing & QA: Jest, Playwright, SonarQube
* DevOps & Infrastructure: GCP, Docker, Terraform, GitHub incl. Copilot
* Architecture: Headless SaaS setup with integrations into Storyblok (CMS), HubSpot (CRM), WeClapp (ERP), BigCommerce (Shop) etc.
* Tooling (optional but welcome): Jira, Xray, Confluence, Miro

Your profile:

* 10+ years of experience as a senior engineer, architect, or tech lead in e-commerce development.
* Proven track record in assessing and stabilizing struggling platforms, ideally involving cloud-native, headless architectures.
* Experience driving large-scale technical overhauls or rebuilds.
* Ability to coach teams, set standards, and drive hands-on solutions.
* Strong experience in:
- Cloud-native GCP architectures
- GCP-based message bus / middleware (e.g., Google Pub/Sub, Cloud Tasks, or similar)
- JavaScript/TypeScript (Node.js, NestJS, React)
- Containerization (Docker), Infrastructure as Code (Terraform)
- CI/CD, automated testing, and code quality tools (e.g., SonarQube)
- Observability (monitoring, logging, alerting)