Lead Backend Engineer Job at cozycozy (Paris)

Lead Backend Engineer

cozycozy

Location:
France , Paris

Category:
IT - Software Development

Contract Type:
Not provided

Salary:

Not provided

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Job Description:

At cozycozy, we’re building the world’s best accommodation metasearch platform, making travel simple, transparent, and inspiring. We already process millions of searches every month and we’re growing fast. To support this growth, we’re looking for a Lead Backend Engineer who will take technical ownership of our backend ecosystem, mentor the engineering team, and act as a key partner to the Head of Engineering on architecture, reliability, and system evolution. If you’re an experienced backend engineer who loves designing scalable systems, guiding technical decisions, and elevating team standards, this role is for you.

Job Responsibility:

Act as the reference engineer for backend topics, supporting the Head of Engineering in driving technical direction
Mentor senior and mid-level engineers, helping them grow through guidance on architecture, best practices, and code quality
Lead technical discussions, design reviews, and RFC processes
Own core backend systems powering millions of real-time accommodation results
Design and maintain scalable, low-latency services ingesting large volumes of data from dozens of partners
Contribute to key architecture decisions and ensure alignment with long-term platform goals
Ensure reliability, performance, and observability across backend components
Write high-quality TypeScript/Node.js and Go code while supporting continuous delivery of new features
Evolve our APIs (REST, gRPC, OpenAPI) to improve speed and performance
Work closely with product, data, and frontend to deliver user-impacting improvements
Partner with DevOps to improve our K8s, Docker, and bare-metal infrastructure (Linux, K3s, CI/CD)
Implement monitoring & alerting using Grafana, Prometheus, Loki
Improve performance, caching, resilience, and horizontal scalability of our systems
Help define coding standards, testing strategy, and workflow improvements
Advocate for strong documentation, observability, and long-term maintainability
Support incident response and help shape reliability practices across the team

Requirements:

Strong experience with Node.js + TypeScript (Fastify, Express, Yarn, Zod, OpenAPI, Jest ) monorepo tooling is a plus
Solid experience with Go (Gin, Zap, code generators) or willingness to deepen your Go skills
Deep understanding of databases: MongoDB, PostgreSQL, Redis/Dragonfly and know Functional Programming Principles
Strong experience with Docker, Kubernetes, and cloud/bare-metal deployments (Linux, K3s)
Experience with queues & event-driven systems (RabbitMQ, Google Pub/Sub, Kafka)
Experience building and maintaining REST (OpenAPI, Swagger), gRPC APIs
Confidence working on big data pipelines, collaborating with data engineers, and creating scheduled jobs with Airflow or k8s Cronjobs
Observability-driven engineer with hands-on experience in Grafana, Prometheus, Loki, and Promtail, and a mindset focused on continuously improving monitoring and insights

Nice to have:

Experience in travel/metasearch, marketplaces, or real-time large-scale systems
Knowledgeable in React (Next.js) for cross-team collaboration

What we offer:

Competitive salary
stock options
Alan health insurance
Swile card

Additional Information:

Job Posted:
January 05, 2026

Work Type:

On-site work

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