Senior Software Engineer, Java

Jobtailor; Köln; Vor Ort; EUR 90.000 - 120.000; Vollzeit

Zusammenfassung

Jobtailor in Köln is seeking an experienced Senior Java Backend Engineer to own the cloud-native platform, evolve microservices, and scale backend systems. You’ll work with Spring Boot, Docker, Kubernetes, and CI/CD tooling to deliver highly available services.

AI-assisted workflows and real-time communications are central to the role. The ideal candidate has 5+ years of Java backend experience, strong knowledge of distributed systems, and fluent English; German is a plus.

Qualifikationen

• Five+ years of professional software development experience with a strong focus on Java-based backend systems.
• Proficiency in modern Java (17/21+), Spring Boot, Spring Framework, JPA/Hibernate, and RESTful API design.
• Experience designing and implementing distributed, cloud-native applications with microservices.
• Hands-on experience with Docker, Kubernetes, and at least one modern CI/CD tool (GitHub Actions, GitLab CI, Jenkins, or Argo CD).
• Experience with at least one major cloud platform (AWS, Azure, or GCP).
• Strong foundations in automated testing, code reviews, and CI/CD practices.
• Good understanding of secure development practices (OWASP Top 10, dependency and secrets management).
• Experience with observability tools for metrics, centralized logging, distributed tracing, and APM.
• Confident operating production systems and participating in incident response.
• Strong analytical thinking and sound technical decision-making in complex distributed systems.
• Fluent English, written and spoken; German is a plus.
• Experience with AI-assisted development tools or openness to using them.
• Experience with CPaaS or cloud communications platforms, telecommunications protocols, or related open-source frameworks is a plus.
• Knowledge of carrier-grade, highly available, low-latency distributed systems is a plus.
• Experience with asynchronous messaging or event-driven architectures is a plus.

Aufgaben

• Take end-to-end responsibility (“you build it, you run it”) for the cloud-native communications platform
• Develop and maintain low-latency call-control systems using FreeSWITCH and Kamailio
• Implement ACD engines and AI-powered IVR workflows
• Integrate real-time AI voicebot platforms via WebSockets/RTP
• Evolve and scale the Java 21+/Spring-based backend platform with microservices and RabbitMQ
• Expand multi-tenant capabilities and maintain usage-rating, billing, and invoicing engines
• Apply secure-coding practices to support ISO 27001 and NIS 2 compliance
• Manage CI/CD pipelines, Kubernetes deployments, and observability to achieve 99.99%+ availability
• Maintain existing Backbone.js and Marionette.js frontends and lead the migration to modern frontend frameworks
• Adopt and promote AI-assisted development tools and agent-based CLI workflows
• Work closely with Platform Engineering, Security, and Product teams

Kenntnisse

Java 21+

Spring Boot

Microservices

Docker

Kubernetes

CI/CD Management

Observability

Secure Coding

Incident Response

Distributed Systems

AI-assisted tooling

WebSockets

Tools

FreeSWITCH

Kamailio

RabbitMQ

WebSockets

RTP

GitHub Actions

GitLab CI

Jenkins

Argo CD

Jobbeschreibung

• Take end-to-end responsibility (“you build it, you run it”) for the cloud-native communications platform


• Develop and maintain low-latency call-control systems using FreeSWITCH and Kamailio


• Implement ACD engines and AI-powered IVR workflows


• Integrate real-time AI voicebot platforms via WebSockets/RTP


• Evolve and scale the Java 21+/Spring-based backend platform with microservices and RabbitMQ


• Expand multi-tenant capabilities and maintain usage-rating, billing, and invoicing engines


• Apply secure-coding practices to support ISO 27001 and NIS 2 compliance


• Manage CI/CD pipelines, Kubernetes deployments, and observability to achieve 99.99%+ availability


• Maintain existing Backbone.js and Marionette.js frontends and lead the migration to modern frontend frameworks


• Adopt and promote AI-assisted development tools and agent-based CLI workflows


• Work closely with Platform Engineering, Security, and Product teams

Requirements

• Minimum of 5 years of professional software development experience with a strong focus on Java-based backend systems


• Solid knowledge of modern Java (17/21+), Spring Boot, Spring Framework, JPA/Hibernate, and RESTful API design


• Experience designing and implementing distributed, cloud-native applications with microservices


• Hands-on experience with Docker, Kubernetes, and at least one modern CI/CD tool (GitHub Actions, GitLab CI, Jenkins, or Argo CD)


• Experience with at least one major cloud platform (AWS, Azure, or GCP)


• Strong foundations in automated testing, code reviews, and CI/CD practices


• Good understanding of secure development practices (OWASP Top 10, dependency and secrets management)


• Experience with observability tools for metrics, centralized logging, distributed tracing, and APM


• Confident operating production systems and participating in incident response


• Strong analytical thinking and sound technical decision-making in complex distributed systems


• Fluent English, both written and spoken


• German language skills are a plus


• Experience with AI-assisted development tools or openness to using them


• Experience with CPaaS or cloud communications platforms, telecommunications protocols, or related open-source frameworks is a plus


• Knowledge of carrier-grade, highly available, low-latency distributed systems is a plus


• Experience with asynchronous messaging or event-driven architectures is a plus

Core Competencies

Demonstrates expertise in developing and maintaining cloud-native communications platforms, with a strong focus on Java 21+/Spring-based backend systems and microservices architecture. Proficient in secure coding practices, CI/CD management, and observability tools to ensure high availability and compliance.

Highest-signal resume keywords

• Java 21+/Spring Development


• Microservices Architecture


• CI/CD Management


• Cloud Platform Experience (AWS, Azure, GCP)


• Secure Development Practices

ATS Optimization Keywords

Hard Skills

• Java


• Spring Boot


• Microservices


• Docker


• Kubernetes


• CI/CD


• Observability Tools


• FreeSWITCH


• Kamailio


• AI-Powered IVR

Soft Skills

• Analytical Thinking


• Technical Decision-Making


• Incident Response

Certifications & Qualifications

• ISO 27001 Compliance

Industry Keywords

• Cloud Communications


• Telecommunications Protocols


• CPaaS


• Distributed Systems


• Asynchronous Messaging

Tools & Technologies

• RabbitMQ


• WebSockets


• RTP


• GitHub Actions


• GitLab CI


• Jenkins


• Argo CD