Software Engineer – Backend, Java

osapiens

Backend Engineer developing Java-based enterprise software for sustainable business growth at osapiens. Contributing to backend architecture, mentoring junior developers, and driving scalable system design in a hybrid work environment.

Posted 6/2/2026full-timeMannheim • 🇩🇪 GermanyMid-LevelSeniorWebsite

Tech Stack

Tools & technologies

CassandraDistributed SystemsElasticSearchJavaMongoDBNoSQLPostgresSOAPSpringSpring BootSpringBoot

About the role

Key responsibilities & impact

Design & Develop: Build and implement Java-based enterprise software with a strong focus on backend architecture and scalable system design.
Own Features: Take full ownership of features from concept to delivery and ongoing support.
Shape Architecture: Contribute to architectural decisions, technical discussions, and design planning in an agile environment.
Mentor & Review: Support junior developers and conduct peer code reviews to uphold high-quality coding standards.
Collaborate & Grow: Work closely within an agile development team, learning from senior engineers and continuously growing your technical and professional skill set.

Requirements

What you’ll need

Passion for Platform Engineering: You’re excited about building scalable, distributed backend systems that create real-world impact for global companies.
Java Expertise: Solid experience with Java or JavaEE, ideally with Spring or Spring Boot frameworks.
Database Skills: Proficiency with relational and/or NoSQL databases such as PostgreSQL, MongoDB, or Cassandra.
API Development: Strong experience building and integrating RESTful and/or SOAP web services.
Test Automation: Experience implementing and maintaining automated tests (unit, integration, end-to-end).
Distributed Systems Knowledge: Understanding of common challenges such as scalability, consistency, and availability.
Modern Engineering Practices: Familiarity with Git and a collaborative, agile mindset.
Bonus Skills: Hands-on experience with search and analytics engines like OpenSearch or Elasticsearch is a plus.

Benefits

Comp & perks

A purpose-driven mission tackling complex sustainability challenges while working alongside global industry pioneers at a fast-growing unicorn company
Room for creativity through collaborative teamwork and an open communication culture
Flexibility and team bonding with our hybrid work options
Fuel for your growth journey, both personally and professionally
Sustainable mobility options, promoting eco-friendly commuting solutions
Fun team events and outings with our global teams
Inspiring workspaces in Mannheim and beyond

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills & Tools

JavaJavaEESpringSpring BootPostgreSQLMongoDBCassandraRESTful servicesSOAP web servicesTest Automation

Soft Skills

ownershipmentoringcode reviewcollaborationagile mindsetcontinuous learningtechnical discussionsdesign planning