Ever wonder how Spotify creates ads that look as stunning in English as in Arabic? How Adidas generates beautifully crafted dynamic creatives for tens of thousands of products? Or how Warner Bros shows billions of ads across the globe on mobile phones, websites, and even TV within milliseconds? The software we create here at Celtra makes this as easy as pie, and we need your help!

We use various tools to craft our products. 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're always on the lookout for exceptional engineering talent - if you're a Software Developer (mid-level or senior-level) who thrives in a collaborative environment, enjoys solving complex problems, and is passionate about building high-impact products, we’d love to hear from you.

On this occasion, we’re hiring across several of our engineering teams, including the AI team. The specific team you’d join will be determined after the initial screening interview, based on your skills, experience and interest.

Your responsibilities:

Mid level:

• Executing tasks of moderate complexity (small projects or parts of big projects).
• Preparing tech specs for simpler/smaller features.
• Mentoring new junior employees and interns, performing CRs and sharing your own perspective.
• Working with the support team to triage incoming client issues.

Senior level:

• Executing complex projects, doing deep and delicate code surgery as needed.
• Preparing clear and concise tech specs for complex features.
• Independently driving a full product cycle for features and improvements.
• Optimizing architecture for maintainability, composability, etc.
• Delegating and supervising smaller tasks.

You will thrive in this position if you have: 

• At least 2-4 years of experience in a similar position, programming and following modern software development processes.
• Experience with modern web technologies (Javascript, TypeScript, CSS, HTML) and frameworks (VueJS / React / Angular).
• Experience with back-end technologies (PHP / Golang, etc.).
• Have a genuine interest in AI/ML (models, agents, …) and exploring new technologies.
• Be proactive, analytical, a good communicator and a team player.
• Have a product mindset.

Why Celtra?

• Impact: Shape the future of creative and help solve some of the biggest challenges ad tech is facing today.
• Culture: We’re bold, collaborative, and proudly a little bit quirky - because doing great work should also be fun.
• Growth: Work with some of the sharpest minds in creative tech, tackle new challenges, and grow faster than you thought possible.

What do we offer?

• Remote working. You can choose to work from home or join us in our Ljubljana office.
• Flexible schedule. You’re trusted to create the right conditions for your best productivity.
• Continuous education. Up to 1000 EUR per year for conferences, books, and courses of your choice.
• Equipment of your choice.
• Knowledge shares. 
• Additional pension and health insurance.
• An additional budget of 500 EUR to set up your home space.
• Employee well-being. Dedicated budget for any kind of wellness activities such as fitness, yoga, etc.

About Celtra

Celtra is redefining digital advertising by making it faster, smarter, and more effective. Our software solutions automate creative production, optimize performance with AI-driven insights, and simplify media activation. Marketers can personalize ads at scale, adapt them for any channel, and leverage real-time data to drive better results. Top brands like Spotify, Adidas, Unilever, Hearst, and Bloomberg trust Celtra to boost engagement, streamline workflows, and maximize ad impact.

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.

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