Senior Backend Developer (Java/.NET)

Solid Company; Polska; Hybrid; PLN 180,000 - 320,000; Full time

Job summary

Solid is seeking an experienced backend engineer to design, develop, and maintain robust REST APIs using Java or .NET, building scalable backend services for client-facing applications. You will work with front-end teams, adopt Docker/Kubernetes/OpenShift, implement secure coding, write unit and integration tests, and participate in Agile sprint activities to drive delivery and reliability.

This role requires 8+ years of backend experience and expertise in Spring Boot or modern .NET, plus strong

Qualifications

• 8+ years of professional backend software development experience.
• Strong commercial experience with Java or .NET.
• Hands-on experience with Spring Boot or .NET Core / modern .NET.
• Strong experience designing and developing REST APIs.
• Experience with Docker and container orchestration platforms such as Kubernetes or OpenShift.
• Good knowledge of SQL and relational databases, including data modelling and query optimization.
• Experience with automated testing, including unit and integration testing.
• Familiarity with CI/CD pipelines and modern software delivery practices.
• Strong understanding of object-oriented programming and software engineering principles.
• Ability to work effectively in cross-functional Agile development teams.
• Fluency in English (both written and spoken).

Responsibilities

• Design, develop, and maintain backend services and RESTful APIs using Java or .NET.
• Build scalable, reliable, and high-performance backend solutions for client-facing applications.
• Design data models and integrate services with relational and NoSQL databases.
• Collaborate with front-end developers to define API contracts and ensure seamless system integration.
• Develop and deploy applications in containerized environments using Docker, Kubernetes, or OpenShift.
• Apply secure coding standards and software engineering best practices.
• Create and maintain unit and integration tests.
• Integrate applications with CI/CD pipelines and automated deployment processes.
• Monitor and optimize application performance, scalability, and reliability.
• Troubleshoot technical and production issues and support their resolution.
• Participate in technical design discussions, sprint planning, code reviews, and other Agile activities.

Skills

English proficiency

Agile development

OO programming

REST API design

Tools

Spring Boot

.NET Core

Docker

Kubernetes

OpenShift

SQL

Job description

• Design, develop, and maintain backend services and RESTful APIs using Java or .NET
• Build scalable, reliable, and high-performance backend solutions for client-facing applications
• Design data models and integrate services with relational and NoSQL databases
• Collaborate with front-end developers to define API contracts and ensure seamless system integration
• Develop and deploy applications in containerized environments using Docker, Kubernetes, or OpenShift
• Apply secure coding standards and software engineering best practices
• Create and maintain unit and integration tests
• Integrate applications with CI/CD pipelines and automated deployment processes
• Monitor and optimize application performance, scalability, and reliability
• Troubleshoot technical and production issues and support their resolution
• Participate in technical design discussions, sprint planning, code reviews, and other Agile activities

Kogo poszukujemy?

• 8+ years of professional backend software development experience
• Strong commercial experience with Java or .NET
• Hands-on experience with Spring Boot or .NET Core / modern .NET
• Strong experience designing and developing REST APIs
• Experience with Docker and container orchestration platforms such as Kubernetes or OpenShift
• Good knowledge of SQL and relational databases, including data modelling and query optimization
• Experience with automated testing, including unit and integration testing
• Familiarity with CI/CD pipelines and modern software delivery practices
• Strong understanding of object-oriented programming and software engineering principles
• Ability to work effectively in cross-functional Agile development teams
• Fluency in English (both written and spoken)

NICE TO HAVE:

• Experience with event-driven or messaging architectures, e.g. Kafka or MQ
• Experience with cloud-native application development
• Knowledge of NoSQL databases
• Experience within financial services, fund administration, or transfer agency environments