TENIOS GmbH
TENIOS GmbH
11 – 50 Employees
ConsultingLogisticsMarketing
Founded in 2001, TENIOS GmbH develops cloud communications solutions for businesses that need flexible voice and messaging infrastructure. Its offering includes voice APIs, AI-powered voicebots, cloud PBX, SIP trunking, and intelligent call routing, enabling tailored customer communication workflows. With a focus on secure, scalable technology, TENIOS supports more than 2,000 companies, including organizations in the insurance and banking sectors.

Senior Java Software Engineer in Cologne (Hybrid)

Build and scale TENIOS GmbH’s cloud communications backend, telephony integrations, and AI voicebot capabilities. Work with distributed Java microservices in a hybrid Cologne role.

Description

  • Own the cloud-native communications platform from development through operation.
  • Develop low-latency call-control systems integrating FreeSWITCH and Kamailio.
  • Create automated call distribution engines and AI-enabled IVR workflows.
  • Connect real-time AI voicebot platforms to telephony workflows using WebSockets and RTP.
  • Scale the backend with Java 21+, Spring-based microservices, and RabbitMQ.
  • Extend multi-tenant features covering isolation, metering, and resource allocation.
  • Maintain and improve usage-rating, billing, and invoicing systems.
  • Apply secure development practices, including OWASP guidance, threat modeling, and dependency scanning.
  • Contribute to ISO 27001 compliance and European NIS2 cybersecurity requirements.
  • Operate CI/CD pipelines, Kubernetes deployments, and observability capabilities.
  • Help maintain platform availability above 99.99%.
  • Support existing Backbone.js and Marionette.js interfaces while guiding migration to modern frontend frameworks.
  • Use and advocate AI development tools and agent-based CLI workflows for coding, refactoring, and delivery.
  • Work closely with Platform Engineering, Security, and Product teams.

Requirements

  • At least five years of professional software development experience, primarily building Java backend systems.
  • Deep knowledge of modern Java 17/21+, Spring Boot, the Spring Framework, JPA/Hibernate, and RESTful API design.
  • Experience architecting and delivering distributed, cloud-native microservice applications.
  • Practical experience with Docker, Kubernetes, and at least one modern CI/CD platform such as GitHub Actions, GitLab CI, Jenkins, or Argo CD.
  • Experience working with at least one major cloud provider: AWS, Azure, or Google Cloud Platform.
  • Strong quality practices, including automated testing, code review, and continuous integration and delivery.
  • A solid grasp of secure software development, including OWASP Top 10, dependency management, and secrets management.
  • Experience with observability across metrics, centralized logs, distributed tracing, and application performance monitoring.
  • Confidence operating production systems and handling incidents.
  • Strong analytical ability and sound technical judgment when working with complex distributed systems.
  • Fluent written and spoken English.
  • German language skills are advantageous.
  • Experience using AI-assisted development tools such as Claude Code or GitHub Copilot, or a genuine willingness to adopt them.
  • Experience with CPaaS or cloud communications, telecommunications protocols such as SIP, RTP, or WebRTC, or related open-source frameworks including FreeSWITCH, Kamailio, or Asterisk.
  • Knowledge of highly available, low-latency, carrier-grade distributed systems.
  • Experience with asynchronous messaging and event-driven architectures using Kafka or RabbitMQ.

Benefits

  • Gross annual compensation of €67,000–€72,000, based on experience.
  • Hybrid work arrangement in Cologne.
  • An international B2B technology setting.
  • Daily opportunities to work with advanced AI solutions and digital tools.
  • A productive international team with quick decision-making and meaningful influence on company growth.

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