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 Hybrid Cologne

Join TENIOS GmbH as a senior Java engineer building cloud-native communications, telephony, and AI voicebot systems. Lead backend services, platform reliability, and the evolution of a highly available communications platform.

Description

  • Own the cloud-native communications platform from development through operation.
  • Build and maintain low-latency call-control systems with FreeSWITCH and Kamailio.
  • Develop advanced automatic call distribution engines and AI-powered IVR workflows.
  • Connect real-time AI voicebot platforms through WebSockets and RTP.
  • Scale Java 21+ and Spring-based backend microservices.
  • Extend multi-tenant architecture through isolation, metering, and resource partitioning.
  • Maintain automated usage-rating, billing, and invoicing systems.
  • Apply secure coding practices aligned with ISO 27001 and NIS 2 requirements.
  • Operate CI/CD pipelines, Kubernetes deployments, and observability systems targeting 99.99%+ availability.
  • Support existing Backbone.js and Marionette.js interfaces while guiding migration to modern frontend frameworks.
  • Use and champion AI-assisted development tools and agent-based CLI workflows.
  • Work closely with Platform Engineering, Security, and Product teams.

Requirements

  • At least five years of professional software development experience, focused on Java backend systems.
  • Strong command of modern Java 17/21+, Spring Boot, Spring Framework, JPA/Hibernate, and RESTful API design.
  • Experience architecting and delivering distributed, cloud-native microservices applications.
  • Practical experience with Docker, Kubernetes, and a 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 GCP.
  • Solid understanding of automated testing, code review practices, and continuous delivery.
  • Knowledge 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 in complex distributed environments.
  • Fluent written and spoken English; German is advantageous.
  • Hands-on experience with AI-assisted development tools or a genuine willingness to adopt them.
  • Experience with CPaaS, cloud communications, telecommunications protocols such as SIP, RTP, or WebRTC, or related frameworks including FreeSWITCH, Kamailio, or Asterisk.
  • Knowledge of carrier-grade, highly available, low-latency distributed systems.
  • Experience with asynchronous messaging and event-driven architectures using Kafka, RabbitMQ, or similar technologies.

Benefits

  • Gross annual salary of €67,000–€72,000, depending on experience.
  • Hybrid working arrangement based in Cologne.
  • Opportunity to serve customers across multiple European markets within a rapidly growing technology company.
  • Regular work with advanced AI solutions and digital tools.
  • International, highly productive team with quick decisions and a direct impact on company growth.

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