Senior Backend / Machine Learning Enginer

Description:

Join us at Nayax, a global fintech leader (NASDAQ; TASE: NYAX) revolutionizing the world of cashless payments, consumer engagement, and business management solutions. With more than 1,200 employees across 12 offices worldwide. At Nayax, you’ll be part of a diverse and innovative community where your work makes a real impact and helps shape the future of payments.

We are currently looking for a Senior Backend / Machine Learning Engineer to design and implement scalable backend systems and integrate machine learning solutions into production. You will work with modern technologies like Node.js, Python, Kafka, MongoDB, and OpenSearch, while driving architectural decisions and CI/CD best practices. This role combines backend engineering excellence with ML deployment expertise.

The Senior Backend/Machine Learning Engineer will report directly to the Director of R&D.

Your key responsibilities will include:

• Architect and develop backend services using Node.js and Python, ensuring high performance, reliability, and scalability.
• Design and implement system architecture for distributed, event-driven systems.
• Build and maintain CI/CD pipelines for automated testing, deployment, and monitoring.
• Integrate and optimize Kafka for real-time data streaming and event processing.
• Design and manage MongoDB schemas and queries for optimal performance.
• Implement and maintain OpenSearch clusters for search and analytics use cases.
• Collaborate with Data Science teams to productionize ML models (model serving, monitoring, retraining pipelines).
• Ensure security, observability, and fault tolerance across all services.
• Mentor team members and contribute to engineering best practices.

• Minimum 6+ years of backend development experience - Must
• Strong expertise in Node.js and Python for production systems - Must.
• Experience with Machine Learning - Must.
• Proven experience in system architecture for distributed applications.
• Hands-on experience with CI/CD pipelines (GitHub Actions, GitLab CI, Jenkins, etc.).
• Deep knowledge of Kafka (producers, consumers, partitioning, scaling).
• Proficiency with MongoDB (schema design, indexing, aggregation).
• Experience with OpenSearch/Elasticsearch (indexing, queries, performance tuning).
• Solid understanding of containerization (Docker) and cloud deployment (Kubernetes or similar).

Nice-to-Have

• Experience with Argo CD and GitOps workflows.
• Familiarity with functional programming languages (e.g., Erlang, Elixir).
• Knowledge of ML lifecycle tools (MLflow, Kubeflow, TensorFlow Serving).
• Observability stack: Prometheus, Grafana, OpenTelemetry.
• Performance optimization and distributed systems troubleshooting.

Tech Stack

• Backend: Node.js, Python, REST/GraphQL APIs
• Data: MongoDB, Kafka, OpenSearch
• Infra: Docker, Kubernetes, CI/CD pipelines
• Bonus: Argo CD, Erlang/Elixir, ML deployment frameworks

Nayax is a global fintech company (NASDAQ; TASE: NYAX) providing an end-to-end platform for payments, consumer engagement, and business operations.

Founded in 2005, Nayax empowers businesses to grow revenue, reduce operational costs, and deliver seamless commerce experiences. Our customer-first mindset and commitment to in-house innovation have positioned us at the forefront of the cashless payment revolution, serving the unattended and retail sectors around the world.

We support over 80 payment methods in 50+ currencies, hold a European payment institution license, and have formed strategic partnerships with global financial institutions to deliver powerful, scalable solutions.

With more than 1,200 employees across 12 global offices, Nayax operates in 62+ countries. Our global headquarters in Herzliya Hills, Israel, is our largest site, housing over 600 employees across 20+ departments — just a short walk from the train station and designed for collaboration and growth.

At Nayax, we believe in creating long-term impact through loyalty tools, omnichannel solutions, and an agile ecosystem of value-added services. We're proud to support businesses in reaching new heights and we're always looking for innovative, passionate individuals to join us.