Jun 15


Can you work with multiple technologies, languages, and frameworks? Are you constantly looking for ways to work smarter, delivering new efficiencies anywhere an improvement can be made? Do you enjoy delivering software quickly adhering to best practices and taking pride in your well-factored code?

If yes, you are very likely the one to enjoy this role!

For our client, an international software company specialising in software products, IT consulting and development offices in Europe and the United States, we are currently looking to add to the team an experienced Senior Back-end Engineer in our Sofia office. In a team with highly qualified colleagues, you will work on a project with US AdTech, connects consumer experiences at scale via media and technology.

About the project

Commerce platform for the open internet connects advertising, marketing, and CX through critical data and engaging digital experiences across platforms ranging from mobile to connected TV. Across Connected TV, Mobile, and Desktop the product empowers premium publishers to create experiences that allow them serving the widest possible audience by optimizing consumers’ time and attention and delivering impactful results for advertisers. As a Back-end Engineer, you will be an important part of the team working on proprietary ad server which is cornerstone technology.

If you’re excited by and have experience working in high traffic environments, building public-facing APIs, and take pride in your well-factored code, this might be the role for you.


  • Develop and launch new capabilities to adapt to evolving business needs
  • Be an active and engaged owner of the product and customer experience, collaborating effectively with Product Management, Data Science, and other disciplines
  • Maintain high standards of code quality, including tests and documentation, and encourage the same by providing constructive code reviews to collaborators
  • Work closely with other engineers to investigate design approaches, prototype new technology and evaluate technical feasibility of new features
  • Manage multiple competing priorities in a fast-paced, exciting environment
  • Troubleshoot and resolve issues, problems, and errors encountered across our various endpoints
  • Provide architectural input when designing new features, both within the ad server, as well as to the overall back-end platform, with an eye toward fault tolerance and low latency
  • Triage and debug operational issues and outages


  • 5+ years of working experience in software development
  • High level of experience with at least one dynamic language (Ruby, Python)
  • Strong knowledge of at least one functional language (Elixir, Scala)
  • Experience writing and communication with back-end services using RESTful APIs, gRPC, or messaging-based systems
  • Strong knowledge of SQL
  • Experience using Git for version control
  • Experience building high traffic, public APIs – a plus
  • Understanding of front-end programming: JavaScript, AJAX, JSON, HTML5 – a plus
  • Experience with AWS (especially DynamoDB and Kinesis) – a plus
  • Passion for following SOLID Design Principles – a plus
  • Experience in the advertising industry, with knowledge of major actors in the ad tech ecosystem (DSPs, SSPs, DMPs, RTB) – a plus
  • At least Upper-Intermediate level of English

Would be a plus

  • High level of self-organization
  • Strong written and verbal communication skills
  • Committed to quality and capable of tracking multiple issues simultaneously
  • Flexibility and initiative

Why us

  • Participate in challenging projects for major global companies
  • Diversity of Domains & Businesses
  • Competitive remuneration
  • Excellent social package – health insurance, food vouchers, etc
  • Active professional community
  • Variety of technologies
  • Positive and friendly work environment in a team of qualified and fresh-minded professionals sharing knowledge
  • Excellent office location close to a metro station
  • Fun work environment

Looks interesting? Send your CV today.

All applications will be treated in strict confidentiality. Only short-listed candidates will be contacted.