Backend Engineer Intern

Ljubljana, Slovenia | Product Development | Part-time | Partially remote


We are looking for an engineer intern that will get an in-depth insight into a diverse stack use in the backend of our products. Depending on your interests, you will have an option to choose what you would like to work on. For example, you can deep dive into our high-throughput services such as an ad server, work on our big-data where you will meet with Spark, Snowflake analytics API, contribute to our rendering engine, work on our REST API and family of background services, CI infrastructure etc.

Your responsibilities: 

  • Depending on your interest, you would be developing a back-end of our products that are used by top companies and thousands of people on a daily basis.
  • Participating in revamping the backend side app architecture.
  • Making sure we maintain a high level of quality by writing automated tests.


  • Some programming skills, and understanding of what APIs are.
  • You are truly interested in how things work and are always willing to dig deeper.
  • Good verbal and written English communication skills.
  • Willingness to constantly learn and improve.
  • Team players.

What brings extra points?

  • Any experience with languages such as Python, PHP, Ruby, Scala, GoLang etc.
  • Understanding and experience with SQL databases, for example MySQL.
  • Familiarity with AWS and it’s services.


What we do 

In the past years Celtra has built two world-class products, Creative Enablement (CE) & Creative Automation (CA)

  • Creative Enablement (CE) 

Creative Enablement is already a growing market leader for a couple of years, helping companies such as CNN, TripAdvisor, Bloomberg, NBCU, ... to enable creativity and improve the quality of their advertising inventory. Our technology enables customers to generate and serve thousands of ads in seconds.

  • Creative Automation (CA) 

Celtra’s younger CA product is chasing a much bigger opportunity by helping brands make content creation better, faster, and more efficient. It is still in the early days of development and lots of features need to be developed, but it already has an impressive list of customers such as Spotify, adidas, Shopify, Unilever, P&G Lululemon… 


At Celtra the end goal is to build great and quality products and make our users’ life easier. We’re on a journey to create something new in the creative technology space. 


What we offer 

In Celtra it’s all about looking beyond the surface, beyond the numbers, and really trying to see the qualities that are at the core of each person, their talents; the discovered ones or better still, the undiscovered 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. 

Our perks and benefits are: 

  • We have a remote-first culture with a possibility to work from the office that offer a dynamic workplace and quality working conditions 
  • We provide plenty of opportunities for interns to grow and develop  
  • We offer a well paid internship
  • We provide employees with top notch working equipment 
  • We provide work-life benefits that allow flexibility at different stages of life