Senior .NET Developer with AWS and React (f/m/x)

Sii Poland; Rzeszów; On-site; PLN 180,000 - 260,000; Full time

Benefits offered by this job

Great Place to Work

Solid financial situation

Contracts with the biggest brands

Centre of internal trainings

Profit sharing

Regular integration events and trips

Medical care

Job summary

Sii Poland is seeking a Senior .NET Developer to join our team and help transform a data‑driven analytical platform in the cloud. You will design scalable architectures and modernize legacy components to ensure performance and reliability.

You will collaborate with diverse professionals worldwide, apply SOA concepts, and contribute to ongoing platform evolution. Strong .NET, web services, AWS, and React/Redux experience are essential, as is excellent written and spoken English.

Qualifications

• Minimum 5 years of experience in software development with a strong focus on .NET technologies.
• Deep expertise in designing and implementing web services.
• Practical experience with AWS and cloud environments.
• Hands‑on mastery of Redux and Context API in React applications.
• Strong understanding of software design principles and best practices.
• Advanced level of English.

Responsibilities

• Contributing to the cloud transformation of a data-intensive analytical platform by designing scalable architectures and modernizing legacy components.
• Ensuring continuous technological evolution of the product by proposing and implementing modern frameworks and architectural improvements.
• Applying Service Oriented Architecture (SOA) concepts in software design and development.
• Providing timely and courteous support to platform users, ensuring issues are understood, analyzed, and resolved promptly.
• Collaborating closely with a team of software engineers, analysts, and quality engineers to design and build software solutions that meet business needs.
• Adhering to team design and coding procedures and standards.

Skills

.NET

Web services

AWS

Redux

Context API

Software design principles

English proficiency

C#

Job description

We are looking for a Senior .NET Developer to join our team and contribute to the cloud transformation of a data-intensive analytical platform. In this role, you will collaborate with innovative and diverse professionals from around the world, designing scalable architectures and modernizing legacy components to ensure performance and reliability.

Your tasks

• Contributing to the cloud transformation of a data-intensive analytical platform by designing scalable architectures and modernizing legacy components
• Ensuring continuous technological evolution of the product by proposing and implementing modern frameworks and architectural improvements
• Applying Service Oriented Architecture (SOA) concepts in software design and development
• Providing timely and courteous support to platform users, ensuring issues are understood, analyzed, and resolved promptly
• Collaborating closely with a team of software engineers, analysts, and quality engineers to design and build software solutions that meet business needs
• Adhering to team design and coding procedures and standards

Requirements

• Minimum 5 years of experience in software development with a strong focus on .NET technologies
• Deep expertise in designing and implementing web services
• Practical experience with AWS and cloud environments
• Hands‑on mastery of Redux and Context API in React applications
• Strong understanding of software design principles and best practices
• Advanced level of English

Nice to have

• Experience with C#

Job no. JOB-KF82T

Sii ensures that all hiring decisions are made solely on the basis of qualifications and competence. We are committed to equal and fair treatment of all, regardless of legally protected characteristics. At Sii, we promote a diverse and inclusive work environment, in full compliance with applicable anti-discrimination laws.

Benefits For You

• Great Place to Work
• Solid financial situation
• Contracts with the biggest brands
• Centre of internal trainings
• Many experts you can learn from
• Open and accessible management team
• Profit sharing
• Passion Sponsorship program
• Regular integration events and trips
• Comfortable and well‑equipped offices
• MySii app
• Medical care