Senior Software Engineer / Architect

Role Overview & key responsibilities

We’re looking for a Senior Full-Stack Engineer to design and scale Kolet’s core backend systems, telecom integrations, and security foundations, while remaining capable of contributing across the stack when needed.

You will work across the stack on user-facing features, backend systems, and internal tools, contributing to telecom-related functionality, new offerings, and customer care automation. You will define technical architecture, review critical design decisions, and ensure long-term scalability, reliability, and security of our platform.

You will play a key hands-on role in shaping and delivering core parts of our platform, from architecture to production.

Missions

• Design and evolve Kolet’s core backend architecture (API design, domain modeling, data flows, scalability strategy).

• Own and maintain telecom integrations (eSIM provisioning providers, roaming partners, multi-IMSI logic, event handling).

• Define and enforce security architecture standards (auth flows, secret management, access control, encryption practices).

• Lead technical decisions on infrastructure, observability, and resilience.

• Build and maintain end-to-end product features, spanning frontend, backend, and integrations.

• Ensure features are reliable, observable, and maintainable in production.

• Help improve developer experience, CI/CD pipelines, and code quality standards.

Key Responsabilities

• Design and review high-quality TypeScript code across backend and frontend.

• Ensure production-grade reliability (monitoring, logging, incident response patterns).

• Design and maintain Node.js APIs supporting B2C and B2B use cases.

• Apply secure coding practices and participate in code reviews with attention to security, reliability, and access control.

• Contribute to raising the overall technical bar through reviews, feedback and shared ownership.

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What We’re Looking For

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👩‍💼 Experience:

• Minimum 8–10 years of professional experience in software engineering, with significant exposure to backend architecture and distributed systems.

• Proven experience designing scalable backend systems.

• Experience integrating third-party APIs in complex domains (telecom, payments, infra-heavy environments).

• Experience handling production incidents and scaling challenges.

🤹‍♂️ Skills:

• Strong expertise in Node.js architecture, PostgreSQL performance & schema design.

• Experience designing secure systems (OAuth, JWT lifecycle, secret management).

• Experience with cloud infrastructure (GCP preferred), CI/CD, containerization.

• Strong understanding of distributed systems and asynchronous workflows.

• Bonus / Nice-to-have

• Experience with NestJS, ReactNative or Next.js.

• Exposure to telecom, payments, or integration-heavy domains.

📣 Languages:

Fluent in French and English.

⭐️ Personality:

You are a senior engineer with strong architectural judgment who thinks in systems rather than features, balances speed with long-term scalability and security, takes ownership of the company’s technical foundations - not just delivery - and thrives in an early-stage startup where pace, pragmatism, and impact matter.