Senior Software Engineer (Java) – Cloud Communications (m/f/d)

SmartTel Plus OÜ; Warszawa; On-site; PLN 234,000 - 279,000; Full time

Benefits offered by this job

Compensation: 21,000-25,000 PLN net +税

Hybrid working model in Warsaw center

Private health insurance

Sports card

International tech environment

AI-focused technology

Influential team

Job summary

Apifonica seeks a senior Java backend engineer to design and build cloud-native microservices using Java 21+, Spring Boot and related frameworks, Docker and Kubernetes. Own services end to end, contribute to CI/CD, observability, security (OWASP Top 10) and incident response in a telecoms/cloud communications domain; collaborate with Platform Engineering and Product in an Agile setup.

Hybrid Warsaw center; 21,000–25,000 PLN net + VAT per month (B2B) depending on experience; private health

Qualifications

• 5+ years of professional software engineering experience with Java backend systems.
• Strong knowledge of modern Java (21+), Spring Boot, RESTful API design.
• Experience designing distributed, cloud-native applications using microservices.
• Hands-on experience with Docker, Kubernetes and CI/CD tooling.
• Security-focused with OWASP Top 10, dependencies and secrets management.
• Fluent English; German is a plus.
• Experience with observability tooling and incident response.

Responsibilities

• Design and implement backend services and APIs in Java 21+ with Spring Boot.
• Build distributed, cloud-native applications using microservices.
• Own services end to end including monitoring, logging and incident response.
• Collaborate in Agile teams, review code and mentor colleagues.
• Apply AI-assisted engineering tools to speed delivery while preserving quality.

Skills

Java 21+

Spring Boot

Microservices

Docker

Kubernetes

CI/CD

Observability

Security mindset

English (fluency)

Tools

GitHub Actions

GitLab CI

Jenkins

Argo CD

Terraform

Job description

In this role you will:

Design & build

• Design and implement backend services and APIs in modern Java (21+), Spring Boot and related frameworks
• Build distributed, cloud-native applications using microservice architectures
• Work with container technologies (Docker) and Kubernetes, and collaborate with Platform Engineering on infrastructure-related changes
• Contribute to CI/CD pipelines and deployment automation

Ship & operate

• Own services end to end following a "you build it, you run it" mindset - including monitoring, logging, troubleshooting and incident response
• Use observability tooling (metrics, centralized logging, distributed tracing, APM) to keep services healthy in production
• Apply secure software development practices, including OWASP Top 10, dependency and secrets management

Collaborate & improve

• Work in Agile product teams (Scrum/Kanban) with a collaborative, ownership-driven mindset
• Review code, mentor colleagues, and help raise engineering quality across the team
• Use AI-assisted engineering tools where useful to speed up delivery without compromising quality or security

Important to know

• You will own services end to end. From design through to running them in production
• Cloud-native and DevOps skills (Kubernetes, CI/CD, observability) matter as much as core Java expertise
• You will work closely with Platform Engineering, Security and Product - this is a collaborative, not a siloed, role
• Our domain is telecommunications and cloud communications, so telecom background is a strong plus but not a requirement
• We use AI-assisted engineering tools as part of our normal workflow and expect openness to them

We’re looking for a person who has:

• 5+ years of professional experience in software engineering with a strong focus on Java-based backend systems
• Strong knowledge of modern Java (21+), Spring Boot, Spring Framework, JPA/Hibernate and RESTful API design
• Experience designing and implementing distributed, cloud-native applications using microservices
• Hands-on experience with Docker, Kubernetes, and at least one modern CI/CD tool (e.g. GitHub Actions, GitLab CI, Jenkins, Argo CD)
• Fast learning curve with a track record of adapting to changing tech stacks
• Solid grounding in software quality practices: automated testing, code reviews, CI/CD
• Good understanding of secure development practices (OWASP Top 10, dependency & secrets management)
• Experience with observability tooling: metrics, centralized logging, distributed tracing, APM
• Comfortable operating production services and responding to incidents
• Strong analytical thinking and sound technical decision-making in complex distributed systems
• Fluent in English (written and spoken); German is a plus

Some nice-to-have skills:

• Practical experience using AI-assisted engineering tools (e.g. Claude Code, GitHub Copilot) or genuine openness to adopting them
• Experience with CPaaS or cloud communications platforms, telecom protocols (SIP, RTP, WebRTC), or related open-source frameworks (FreeSWITCH, Kamailio, Asterisk)
• Familiarity with carrier-grade, highly available, low-latency distributed systems
• Experience with asynchronous messaging / event-driven architectures (Kafka, RabbitMQ)

Why Apifonica?

What we offer

• Compensation: 21,000-25,000 PLN net + VAT/month (B2B), depending on experience
• Hybrid working model based in the very center of Warsaw
• Private health insurance package and sports card coverage (details will be provided during the recruitment process)
• An international B2B technology environment: working with clients from various European markets within a rapidly growing technology company
• Focus on artificial intelligence and technology: day-to-day work with cutting-edge AI solutions and digital tools
• An influential team: an international, highly productive team with a fast decision-making process and a tangible impact on the company’s growth

Apifonica is a communications automation platform that has been operating in the market for over ten years. AI agents, messaging, voice services and numbers operate on our own telecoms infrastructure, managed by Tenios - a company within our group and a licensed German operator that has been operating in the telecoms sector since 2001. A single contract and a single SLA cover all channels, and a single team is responsible for both the AI logic and call quality.

Every month, we handle over 250 million calls and 70 million messages for more than 1,800 business clients, including MAN, ERGO, Toyota, Generali and Leroy Merlin. Our teams are based in Germany, Poland and Latvia; our head office is in Tallinn; and our infrastructure remains in Europe - it is located in Frankfurt, is ISO/IEC 27001:2022 certified and complies with GDPR requirements.