Svitla Systems Inc. is looking for a Senior/Principal Back End Developer with Matrix for a full-time position (40 hours per week) in Poland. Our client is a digital identity platform that empowers individuals to own and manage their personal information online securely. It allows users to create a portable digital identity that they fully control, eliminating the need for multiple usernames and passwords across different platforms. Users can obtain verifications from trusted entities, such as banks or educational institutions, to authenticate aspects of their identity, enhancing trust and security in digital interactions. The platform offers encrypted messaging and document sharing, ensuring users can communicate and exchange information safely. The solution includes a digital wallet feature, enabling users to manage various digital assets and currencies within the same secure environment.

The project involves rebuilding the messaging system using the Matrix protocol – an open, secure, and decentralized standard for real-time communication. The client is looking for a Principal Engineer with deep experience in the Matrix ecosystem to lead the backend development and integration of their new messaging system. This role will focus on backend infrastructure and protocol-level integration, tackling key challenges such as token handling, session reliability, federation stability, and secure communication.

Requirements

• 8+ years of experience in software engineering.
• 4+ years of hands-on experience with the Matrix protocol (mandatory).
• Deep knowledge of Matrix APIs, federation, and encryption mechanisms.
• Solid understanding of backend development with Python, Go, or Node.js.
• Strong knowledge of secure communication principles and real-time systems.
  
  

Nice to Have

• Experience with other decentralized communication protocols.
• Contributions to the Matrix ecosystem.
• Experience with bridging services (e.g., IRC, Slack, Discord).
• Understanding of decentralized identity (DID, SSI).
• Open-source project involvement or standards body participation (IETF, W3C).
  
  

Responsibilities

• Lead Matrix protocol backend integration and ongoing maintenance.
• Work with Matrix server implementations such as Synapse or Dendrite.
• Deeply understand and apply Matrix APIs, federation, and authentication flows.
• Integrate Matrix into the backend stack (Python, Go, Node.js).
• Address token handling, session management, reliability, and scaling.
• Ensure a secure and robust communication infrastructure.
  
  

We offer

• US and EU projects based on advanced technologies.
• Competitive compensation based on skills and experience.
• Annual performance appraisals.
• Flexibility in workspace, either remote or in our welcoming office.
• Comprehensive medical insurance after one month.
• MultiSport card with access to 2500 sports facilities all over Poland
• Bonuses for article writing, public talks, other activities.
• 15 vacation days, 10 national holidays, sick leaves, family days off.
• Personalized learning program tailored to your interests and skill development.
• Free webinars, meetups and conferences organized by Svitla.
• Gifts for anniversaries, New Year, children and more.
• Fun corporate celebrations and activities.
• Awesome team, friendly and supportive community!