Senior Developer

Cerillion, founded in 1999, is a leading provider of billing, charging and customer management systems, delivering its solutions across a broad range of industries.  Cerillion’s main offices are in London, UK, Pune, India and a newly established office in Sofia, Bulgaria.

As part of our ongoing expansion, Cerillion Bulgaria is looking for a Senior Developer to join our development team in Sofia. This role is ideal for a hands-on technologist who enjoys tackling complex business challenges and delivering high-quality software solutions. The successful candidate will be responsible for technical design, development, and delivery of enhancements to Cerillion’s core BSS/OSS products.

The team at Cerillion has already produced innovation in the fields of Cloud billing, Subscription Management, Mediation, Convergent Charging, Mobile Billing, Content Billing, Real-time Rating, Product Catalogue, Mobile App and Self Service.

This is an excellent opportunity for a passionate developer who enjoys working with leading-edge technologies in a dynamic, collaborative environment. You’ll be part of a global team developing solutions that are transforming telecoms, cable, and finance industries. International travel may be required occasionally.

Responsibilities: 

• Understand customer business and R&D requirements.
• Analyse existing system functionality and design gaps.
• Participate in requirements and design discussions with architects and analysts.
• Design and develop customisations to Cerillion’s core BSS products, including CRM, Mediation,
• Charging and Rating, Billing, Bill Printing, Credit Control, Provisioning, Product Catalogue, and Self
  Service.
• Develop new R&D; features and modules for inclusion in the product suite.
• Perform code reviews, unit testing, and ensure compliance with development standards.
• Work collaboratively in Agile environments and contribute to sprint planning and estimations.
• Support bug fixing, performance optimisation, and integration testing.
• Provide build and release instructions to DevOps and QA teams.
• Support build and deployment processes, ensuring smooth release cycles and quality assurance.
• Report project/task status, risks, and issues to the Software Engineering Manager.
• Mentor developers and assist in technical troubleshooting and solutioning.
• Contribute to technical design documentation and best practice guidelines

Requirements

• Educated to degree level (or equivalent) in Computer Science, Software Engineering, or a
  related discipline.
• Extensive experience in software design and development using Java-based technologies.
• Experience in technical leadership or senior developer roles.
• Experience working on high-transaction, large-scale systems in telecoms, billing, or similar enterprise
  domains preferred.
• Strong expertise in Java, Spring Boot, and J2EE.
• Hands-on experience with RESTful APIs, Microservices, and Containerisation (Kubernetes/OpenShift).
• Solid understanding of RDBMS, SQL, and PL/SQL.
• Experience with Angular, JavaScript, Bootstrap, HTML5, and CSS3.
• Familiarity with application servers such as JBoss or Oracle 10gAS.
• Proficiency in Git-based source control, debugging, and build tools (e.g., Maven, Jenkins).
• Knowledge of software development lifecycle (SDLC) and Agile methodologies.
• Quick learner with excellent analytical and troubleshooting skills.
• Strong verbal, written, and documentation communication abilities.
• Team player with collaborative spirit and mentoring capability.
• Highly self-motivated, quality-focused, and proactive in problem-solving.
• Organised, disciplined, and able to manage multiple priorities effectively.

Desirable

• Exposure to JBoss Fuse/Apache Camel, DROOLS (JBoss Rules), or Business Intelligence platforms.
• Experience with C/Pro*C on UNIX environments.
• Knowledge of Telecom BSS/OSS, Mediation, Billing, or Online Charging systems.
• Understanding of Cloud-native architectures and DevOps pipelines.
• Demonstrates leadership and initiative in driving innovation and process improvement.
• Skilled in estimation, planning, and agile delivery practices.