Senior Fullstack .NET Developer (f/m/x)

Since 2015, we have been recognized with the Great Place to Work title every year, a prestigious award based on employees feedback. According to the study, over 89% of people working at Sii consider it a fantastic place to work.

We began as a one-person start-up in 2006 and grew into a 7 500 workers company in 2025, generating revenue of PLN 2.1BN, having no debts, and being recognized as the leading IT services provider in Poland by the Computerworld TOP200 report. Check out more facts that prove our market strength.  

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We are a key partner for many prestigious global companies from different sectors i.a: BNP Paribas, KUKA, ING or Bombardier with whom we have contracts that guarantee continuity of employment for our workers.  

Our own training center organized around 300 technical and soft skills training courses last year. More than 3 300 people took part and rating them at 4.7/5. Trainings are conducted by practitioners, both experts from Sii and outside the company. Our employees can also request for individual external courses. 

At Sii we have a lot of knowledge sharing initiatives – our workers can join technology Communities, participate in a mentoring program or benefit from in-house trainings, blog and e-learning platforms.

No matter our title, we address each other by first names. Transparency and dialogue are important for us, that’s why we periodically organize local CEO meetups, online CEO live sessions and departmental Inspiration Days. During them everyone has the opportunity to meet with people managing the company, ask questions, report problems and discuss troubling issues.

Sii shares its profit with employees to thank everyone for a great year and results. We know that without the huge commitment of Power People, the company’s success would not be possible. From 2022, over PLN 76 M has already been allocated for this aim. 

We allocate PLN 1M annually for the development of passions and hobbies through our Passion Sponsorship & Volunteers programs. Thanks to this funding, 25% of our Power People pursue their dreams each year – such as climbing Mont Blanc, running races in the most remote corners of the world, or sending a balloon into the stratosphere.

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Every year we organize more than 700 events, allocating for this aim bugdet exceeding PLN 15M. We take care not only for integration of our workers, but also we provide entertainment for their families within regular St. Nicholas Days, Family Picnics, Carnival Balls.   

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We have A+ class offices in the centers of 14 Polish largest cities, allowing easy access for both our employees and clients, from anywhere in the country and the world.   

Project rooms, meeting rooms, modern equipment, relax and childcare area or even a slide – these are just some of the facilities we offer. 

Work smarter, not harder – guided by this idea we have developed an app for our employees that simplifies all administrative activities. It take just a few clicks on the phone to submit a holiday request, report on working time or track reminders for upcoming tasks.

The app is also available for candidates. You can download it for both iOS and Android. 

We offer private healthcare packages to our workers, with access to more than 5 000 specialists. The option also includes dental services and the possibility to add family members.