Java Developer (m/f/d)

Introduction

About us

At Optimax Energy, we have been developing smart solutions for automated trading systems and promoting the transition to green energy for over 10 years. This makes us a leader in international electricity trading.
Our culturally diverse team shares a common vision and fosters a culture of appreciation and equal opportunities. We believe that we can achieve extraordinary things if we develop freely. That's why we place great value on a healthy work-life balance and encourage creative freedom.
We embrace diversity, equality and inclusion. Different perspectives and backgroundds strengthen our team and lead to creative solutions. To achieve this, we create an appreciative working environment that recognizes the uniqueness of all employees and retains talent in the long term.
In order to actively shape the future of the energy sector, we are looking for outstanding, committed individuals who share our vision and corporate culture.

Your responsibilities

Our team is responsible for providing robust automation and integrations necessary to facilitate algorithmic energy trading.
As Java Developer in this team, you will play a crucial role in maintaining and enhancing our existing services while driving innovation by:

• Developing and maintaining backend services that provide essential market data for trading decisions, ensuring system reliability, scalability and overall software quality.
• Implementing new features and improving existing systems to support market expansion.
• Conducting code reviews and collaborating with peers to maintain high-quality standards.
• Writing technical documentation for internal knowledge sharing.
• Troubleshooting and debugging to resolve reported issues.
• Gathering and refining requirements by directly collaborating with stakeholders.

Status Quo

We work with the following tech stack:

• Java, Spring Boot, MySQL, Clickhouse, Kafka.
• Integrations: HTTP, AMQP, WebSockets, R Sockets, STOMP and email; using JSON, CSV, XML, EDI and other formats.
• CI/CD: GitLab, Maven, Jenkins, TestContainers, SonarQube, Portainer and Kubernetes.
• Monitoring: Micrometer, Grafana, Graylog.

Your skills

Must-Haves

• At least 5 years of professional software development experience, including 3+ years in Java (version 11+).
• Understanding and regular use of software design patterns.
• Confident usage of Git in day-to-day workflows.
• Familiarity with unit and integration tests.
• SQL skills for writing queries and understanding of relational databases.
• Experience designing and consuming API services.
• Experience building and managing Java projects with Maven.
• Familiarity with threads, Java Executors, concurrency models and asynchronous programming.
• Good communication skills in English (B2)

Nice-to-Haves 

• Experience with message brokers and asynchronous messaging in general (e.g., RabbitMQ, Apache Kafka).
• Familiarity with agile methodologies (Scrum, Kanban).
• Performance tuning, profiling, and optimization.
• Experience with Docker, Jenkins, CI/CD pipelines.
• Knowledge of Spring Boot.
• Background in energy markets or trading.

What we offer

Health & well-being:

• Freshly cooked lunch every day
• Massages and Pilates in the office
• EGYM Wellpass
• Sports and mobility offers, such as subsidies for a new bike
• Company health insurance that gives you access to additional healthcare services

Flexible working arrangements and benefits:

• 30 days paid vacation
• Flexibility in working hours depending on company needs
• Additional vacation for the honeymoon
• Subsidies for childcare

Team culture and working atmosphere:

• Regular team events (game night, table tennis tourmaments, excursions, etc.)
• Work in a mission-oriented, international team that values diversity and equality
• Working atmosphere with open doors and flat hierarchies
• Modern, green office in the heart of Leipzig

Professional development and further training:

• Independence and responsibility in project management
• 10% of weekly working time for personal and professional development