Senior AI Fullstack (C#, .NET)

We are Primotly - a software house based in Warsaw but we’re not just building software - we’re building relationships that last. If you’re ready to lead exciting international projects and help brands bring their vision to life, let’s talk.

We are looking for a Senior AI & Full-Stack Developer (C#, .NET, AI). We are looking for someone who is proactive, self-motivated. You'll be comfortable getting up to speed quickly, taking ownership of your work and working independently, without requiring close supervision.

At the same time, we value collaboration and curiosity. The ideal candidate is confident in finding solutions and navigating challenges independently but is also comfortable asking questions, sharing ideas and seeking support when needed. 

Fluency in English is required, as you will collaborate with an international team.

The ideal candidate 🌟

We are looking for a senior-level developer with strong experience in full-stack software development and AI integration. The ideal candidate will have a solid foundation in software engineering, data processing, automation, API development, and modern AI technologies.

This is a hands-on role for a proactive and self-driven individual who enjoys working across a varied technology stack and collaborating with cross-functional teams. You'll have the opportunity to tackle complex business challenges, build innovative solutions within a dynamic and supportive environment. If you enjoy solving problems, learning new technologies and turning ideas into practical outcomes, we'd love to hear from you.

Technical Requirements:

✅ Strong commercial experience in C# and ASP.NET  Web forms / MVC / .NET Core, IIS Hosting and management.
✅ Solid HTML, CSS, JavaScript, and modern web development practices
✅ Strong MS SQL Server and relational database design
✅ Practical experience integrating with Large Language Models (LLMs): LiteLLM proxy and LLM API integrations
✅ Experience using OpenAI, Anthropic (or similar)
✅ Experience building automation workflows and windows services
✅ Experience designing and consuming REST APIs
✅ Strong understanding of data transformation and ETL processes

About You

🚀 A senior-level professional who can take ownership of projects from concept through to implementation, working with minimal supervision while collaborating effectively within a team environment.

🧠 Goal-oriented and self-motivated, with strong analytical, problem-solving, and decision-making skills. You proactively identify opportunities for improvement, drive innovation, and tackle technical challenges with confidence.

🔄 Comfortable managing multiple projects, priorities, and technologies at the same time, with the flexibility to adapt quickly in a fast-paced environment where requirements and priorities can evolve.

🤝 An excellent communicator who can work effectively with both technical and non-technical stakeholders, translating business needs into practical technology solutions and collaborating closely with teams across research, operations, analytics, and delivery.

About the client:
One of the world's leading market research companies, providing data insights and consulting services to help clients make smarter decisions. With a presence in over 90 countries, they combine research expertise and innovative analytics to understand people, markets, and society.

Important note:

B2B Rate: 165-195 pln /h

Here’s what we offer within the B2B cooperation:

➕ You can expect a B2B contract (rate: 165-195pln /h). We will evaluate your experience on our technical interviews.

➕ Regardless of your current insurance, we want to ensure your comfort. That is why we provide access to co-financed private healthcare for our B2B partners.

➕ Not only are your skills substantial, but also your growth! We highly encourage you to take part in meet-ups, online courses, conferences, and external training.

➕ A healthy mind in a healthy body – we support your overall wellness by offering access to a sports card on partnership terms.
➕We focus on outcomes and clear milestones. Cooperation hours and remote work setups are highly flexible, making it easy to align with your rhythm. 

➕ To ensure seamless project execution, we offer the possibility of corporate hardware and software provision for the duration of our contract.

Here is what the recruitment process looks like:

Step 1: HR CV review and getting in touch

Step 2: First Interview (30 minutes)

Step 3: Second interview (one hour Technical Interview)
Step 4: Client interview

Step 5: Negotiations ;)