Software Developer Intern
First seen by Alion on Jul 13, 2026.
Please note that a valid student status in Slovenia is required for this position.
At Celtra, we’re leading a creative revolution. In a world where digital content consumption is skyrocketing and audience expectations evolve daily, traditional production models can no longer keep up - and that’s where we come in. Our creative solutions help media owners and operators monetize inventory more effectively, bridge the creative supply gap for brands and agencies, and deliver faster, smarter, and more personalized experiences. We’re not just keeping up with industry shifts - we’re setting the pace.
Now, we’re looking for a Software Developer Intern who will have an opportunity to work on our products, used by top companies and thousands of people on a daily basis. You will be joining one of our cross-functional teams and, with the support of our mentors, you will get your hands dirty by working on some interesting projects.
What tools do we use?
On the backend, you can find Scala, NodeJS, PHP, MySQL, Spark, Snowflake, and also MongoDB, Kinesis. On the frontend, we use Vue.js, Typescript and Vanilla JS when needed. Everything runs on the AWS cloud, and the ECS cluster orchestrates it. We also love CI/CD, IaC and do daily deployments to ensure your contributions see the light of day as soon as the QA team is happy.
We also actively embrace AI-assisted development with Cursor to boost productivity, iterate on PoCs and explore new ways of building software.
Your responsibilities:
- Developing frontend and backend of our products that are used by top companies and thousands of people on a daily basis.
- On the frontend you will be implementing rich experiences in our apps, participating in revamping the client-side architecture and general redesign of the product frontend.
- On the backend you will mainly work on our APIs (REST, web sockets) and family of background jobs.
- Making sure we maintain a high level of quality by writing automated tests.
Qualifications
- Understanding of RESTful API architecture.
- Knowledge of HTML5 and CSS.
- Knowledge of JavaScript.
- Knowledge of at least 1 backend programming language (Python, PHP, Ruby, Java, Go, Scala …).
- Good verbal and written English communication skills.
- Willingness to constantly learn and improve.
- Team player.
- Active student status in Slovenia.
What brings extra points?
- Knowledge of Vue.js.
- Knowledge of global state management concepts.
What we offer?
- Buddy and mentor that will help you grow professionally, plus a well structured development plan.
- Flexible working hours and hybrid work based on a fixed number of in-office days.
- Top-notch working equipment.
- Regular team & company events.
- Free breakfasts & beverages available in the office.
About Celtra
Celtra helps enterprise advertisers, media, and agencies design, approve, and deliver digital creative across the ever-growing number of campaigns, markets, designs, and variants. Celtra’s Creative Automation & Enablement Software helps brands move faster than ever while dramatically scaling content production. Companies like adidas, TripAdvisor, Spotify, Unilever, NBCU, Lululemon, YETI, Vice, and hundreds more partner with Celtra to cut production costs while increasing efficiencies and output in the cloud.
Empowering Creativity through Diversity & Inclusion
Our mission is to empower creativity - and we cannot fulfill our mission without different perspectives. Diversity drives innovation, and Celtra is committed to diversity, equity, inclusion, and belonging.
Every employee is empowered at Celtra - no matter your race, age, religion, gender identity, sexual orientation, physical or mental ability, or ethnicity. We hire the best, and develop our teams through continuous education and mentorship, in a community where everyone can bring their whole selves to work.