QA Engineer, Backend

Ljubljana, Slovenia | Product Development | Full-time


We are searching for a Backend QA Engineer that will help us solve our  challenges of scale, integration, quality, and agility. We provide the best Creative Management Platform on the market. Our customers are the biggest brands and publishers in digital advertising.


Our challenges are:

  • Scale: We’re serving hundreds of millions of creatives every day across the globe. Our servers are expected to handle 100k requests every second.
  • Integration: Our platform integrates with dozens of external partners and services. Assuring the quality of the Celtra platform often means assuring the quality of services we depend on.
  • Quality: The tools we deliver must meet the security, reliability and performance  expectations of the biggest brands in the industry.
  • Agility: We push major updates on a weekly and minor on a daily basis, all while maintaining > 99% uptime.



Technical Knowledge

  • UNIX/Linux: You are proficient in the use of command-line tools for system configuration and administration. Experience with containerization and container orchestration is a plus.
  • Networking: You understand TCP/IP and HTTP protocols. Our backend systems distribute load geographically, as well as within individual data centers. We also integrate with a number of external partners. Ability to understand underlying load distribution and traffic routing technologies to assure quality at scale is a must.
  • Scripting: Our day-to-day tools we use are written in Bash, Python and Coffeescript. Ideally, you’ll have written moderate complexity scripts in at least two of these languages. Using them to write maintainable, well-designed testing suites is a plus.
  • Test Plans: You can understand product specifications and write a test plan based on them. You can also scope regression tests based on reviewing code changes.


  • You care about your users: As part of the QA team, you will be the first and foremost advocate for our users. Their time and pains should always be your first concern.
  • You are a critical thinker: You do not take claims at face value. Instead, you look for ways of prove or dispel them. You can break problems down into smaller, individually verifiable hypotheses and prove them with tests and experiments.
  • You are curious how things work: Celtra’s tech stack is extensive and you will be encouraged to dig deep into an issue. You enjoy reverse engineering complex systems just as much as building them. Curiosity and a hacker attitude is a must.


About Celtra

We are a hi-growth AdTech company with 180+ employees around the globe with offices in Boston, New York, San Francisco, London, Ljubljana and Singapore. Celtra is self-service enterprise software for automating and scaling creative production. Celtra enables creative and marketing teams to design, approve, and deliver digital creative across the ever growing number of channels, ad formats, variations, and markets. Companies like VICE, Unilever, Lululemon, CNN, and Hearst partner with Celtra to cut production costs while increasing efficiencies and output in the cloud.

Here it’s all about looking beyond the surface, beyond the numbers, and really trying to see the qualities that are at the core of the person, their talents; the discovered ones or better still, the undefined ones. We look for people who naturally want to take responsibility for their own success, and strive to do something that has a tangible impact. To our best talent, we give the freedom to do the unusual.

We take good care of our people.

  • We offer a competitive benefits and compensation package
  • We place great importance on the professional development of our employees
  • We provide employees with top notch working equipment
  • We provide work-life benefits that allow flexibility at different stages of life
  • We offer a dynamic workplace and quality working conditions
  • We provide plenty opportunities for employees seeking a more active lifestyle