Do you enjoy designing software that runs quickly and smoothly at scale? At Twake Mail & Twake Calendar, we build open-source communication and collaboration products centered around scalability, open standards, and digital sovereignty. We are looking for a Senior Backend Engineer who can confidently navigate large codebases, deliver reliable and maintainable code, and quickly develop autonomy in a demanding engineering environment. Beyond implementation, we value engineers who bring critical thinking, sound technical judgment, and real ownership to what they build, people who understand systems deeply, not just generate code from prompts. If this sounds like you, this is perfect timing to join us!

KEY RESPONSIBILITIES 
In this role, you will actively contribute to the open-source Apache James and Sabre DAV projects, as well as our Twake Mail and Twake Calendar products, by: 
- ​​Helping to maintain and develop new features for these solutions. 
- Adapting, customizing, and providing support for Twake Mail for new deployments 
- Providing technical support to client projects using Apache James technology.

QUALIFICATION 
• A good level of Java is required. An understanding of Scala and some knowledge of PHP are a plus. 
• The candidate must be able to adapt to a demanding environment where high-quality, reliable, tested, documented, and well-structured code is expected. 
• Be comfortable working with large codebases. 
• Familiarity with open email standards is a plus (IMAP, SMTP, JMAP, Cal/CardDAV, OpenIDConnect, etc.). 
• Familiarity with SQL and NoSQL data management tools is expected. We work with technologies such as Cassandra, PostgreSQL, S3 compatible, MongoDB, OpenSearch, RabbitMQ, Redis, and OpenLDAP. 
• A good understanding of operational challenges is expected, both in terms of technical aspects (Kubernetes, Ansible, performance, etc.) and functional aspects (specific to email). 
• An awareness of frontend and mobile development challenges is a plus (ReactJS/Flutter). 
• Good level of English communication

Soft Skills 
• Ability to communicate actively (communities, conferences). 
• Results and quality-oriented, rather than rigid process-driven 
• Ability to collaborate in an international and multicultural environment 
• Flexibility and adaptability depending on the project 
• Passion for the product and attention to detail 
• Motivation to create a simple, reliable, and useful tool for users 
• Proactive mindset

• Involved in OpenSource community you follow your digital sovereignty ideal 
• Collaboration with a diverse, highly skilled international team that values knowledge-sharing and innovation 
• Opportunities to attend specialist conferences 
• Access to internal learning resources, refresher courses to keep your skills up to date 
• Freedom of a hybrid work model that balances remote and in-office work. 
• Additional health insurance with extensive coverage and employee-centric benefits; annual health check-ups 
• Competitive salary package, including a 13th-month bonus and lunch allowance 
• Exciting company outings, team-building activities 
• Modern working space filled with natural light 
• Free coffee & tea

1. Global community & continuous learning
2. Competitive salary & hybrid flexibility
3. Premium health care & international team