Infrastructure Engineer (various levels)

Ljubljana, SI

About us

Celtra’s SaaS product is used to build and host the highest quality, data-driven video and interactive display ads for 2/3 of Fortune 500 brands. Our servers can handle 100k requests per second, many of which fan out to other services, internal and external. Any downtime costs our advertisers thousands of dollars per minute, and costs us even more in reputation. 

Job description

We are looking for infrastructure engineers (aka DevOps / SRE) of various experience levels — from young distributed computing enthusiasts that will explain the benefits of the latest developments in Linux containerization, to wise elders that will teach us about queueing theory and error propagation — to help us grow another order of magnitude or two.

You will be part of our DevOps team, which is responsible for our product’s availability, latency, performance, efficiency, monitoring, emergency response and capacity planning.

Your development responsibilities will be to:

  • Design, develop and maintain software that handles deploying, scaling and monitoring of our product.
  • Establish design patterns and best practices for building new product features in a scalable and reliable way.
  • Help developers apply those patterns and participate in early stages of feature design, when needed.

 Your operational responsibilities will be to:

  • Be on-call a portion of your time to get your hands dirty and gain experience.
  • Help developers diagnose production issues and hunt down elusive bugs.
  • Ensure uptime objectives are met by participating in controlling the risks and rate of change in collaboration with the QA team.


You must have experience in both: 

Software development

  • Programming languages
  • Software architecture
  • Debugging and profiling
  • Database design
  • Version control; as well as

 System administration

  • Unix philosophy and internals
  • Networking
  • Databases
  • Log management
  • High-availability

This means you must have designed and written software of some non-trivial complexity, as well as been responsible for keeping things running in production.

You must also have a strong passion for cloud computing. Things like containerization, type-1 hypervisors, Infrastructure as a Code, Serverless infrastructure and twelve-factor apps should get you excited!

Other requirements:

  • Fluent written and spoken English - you will be using it every day.
  • A continuous learner and a critical thinker.
  • A responsible individual capable of teamwork and communication.
  • A fun, open-minded person. Extensive GIF-posting skills are a big plus! 

Our offer

You will be joining a diverse, highly innovative and creative team of developers, designers and managers from all over the globe:

  • We care deeply about our product, company and its people.
  • We believe in high standards and long term code quality.
  • We ship. Features and fixes are deployed weekly.
  • We believe in an open and proactive culture where engineers are expected to learn and contribute in ways outside the usual coding assignments.
  • We always follow the latest technology trends and constantly research and learn new things.

We take good care of our people:

  • Receive a highly competitive base salary, benefits and quarterly bonuses for performance.
  • Enjoy a generous education budget for conferences, classes, literature or studies.
  • Choose your equipment.
  • Work in our cosy office in the very center of Ljubljana, Slovenia.
  • Our fridge is always full and we drink the best coffee.
  • Travel between US and Europe.
  • Not from around here? No problem: If you are the right person, we are more than willing to help you relocate.


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