Senior Back End Engineer

Castillians

. Design, develop, and maintain scalable and reliable server-side applications using C# and the .NET framework .

Posted 10/27/2026contractRemote • IrelandSeniorWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates expertise in backend software engineering with a strong focus on C#, .NET framework, and RESTful API development. Proficient in optimizing application performance and collaborating with cross-functional teams to deliver scalable and reliable solutions.

Highest-signal resume keywords

C# Programming.NET FrameworkRESTful API DevelopmentPostgreSQL Database ManagementCloud Platforms (Microsoft Azure, AWS)

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills

Backend Software EngineeringMicroservices ArchitectureSQL Query OptimizationObject-Oriented Programming (OOP)Software Design PatternsDistributed SystemsTesting and DebuggingPerformance OptimizationContainerization (Docker)Version Control (Git)

Soft Skills

Analytical SkillsProblem-Solving SkillsEffective CommunicationCollaborationIndependence

Tools & Technologies

KubernetesRedisApache KafkaRabbitMQGRPC

Industry Keywords

Payment SystemsHigh-Availability ApplicationsService DiscoveryDistributed CoordinationDomain-Oriented Services

Tech Stack

Tools & technologies

ApacheAWSAzureCloudConsulDistributed SystemsDockerGRPCJavaScriptKafkaKubernetesMicroservicesNoSQLPostgresRabbitMQRedisSQL.NET

About the role

Key responsibilities & impact

Design, develop, and maintain scalable and reliable server-side applications using C# and the .NET framework
Develop and implement secure RESTful APIs and microservices for client applications, payment services, and system integrations
Collaborate with frontend developers, product managers, and engineers to translate business requirements into technical solutions
Design, implement, and maintain distributed systems comprising multiple domain-oriented services
Perform testing, debugging, and code reviews
Optimise application performance, scalability, and reliability through code improvements, caching strategies, and database optimisation
Design, write, and optimise SQL queries
Work with relational and NoSQL databases, including PostgreSQL and SQL Server
Contribute to deployment and maintenance using cloud platforms, containerisation technologies, and orchestration tools
Apply object-oriented programming principles, software design patterns, and backend development best practices
Improve development processes, system architecture, and delivery efficiency with engineering teams
Stay current with emerging technologies and contribute to continuous improvement of backend engineering practices
Complete a project-specific technical assessment, if required

Requirements

What you’ll need

At least 5 years of experience in backend software engineering, backend development, or a similar role
Strong hands-on experience with C# and the .NET framework
Experience designing, developing, and maintaining RESTful APIs and microservices
Understanding of distributed systems and architectures comprising multiple domain-oriented services
Experience with relational databases, particularly PostgreSQL and SQL Server, including writing and optimising SQL queries
Familiarity with NoSQL databases and data management concepts
Experience with cloud platforms such as Microsoft Azure or Amazon Web Services (AWS)
Familiarity with Git and version control practices
Experience with Docker and container orchestration technologies such as Kubernetes
Strong understanding of object-oriented programming (OOP), software design patterns, and clean code principles
Understanding of frontend technologies, including HTML, CSS, and JavaScript
Strong analytical and problem-solving skills, with the ability to troubleshoot complex technical issues
Effective written and verbal communication skills in English
Ability to work independently while collaborating effectively with cross-functional and international engineering teams
A bachelor's degree in Computer Science, Information Technology, Software Engineering, or a related field (nice to have)
Experience with distributed systems and messaging technologies such as Apache Kafka and RabbitMQ (nice to have)
Familiarity with caching technologies such as Redis (nice to have)
Experience with gRPC for service-to-service communication (nice to have)
Knowledge of service discovery and distributed coordination tools such as Consul and etcd (nice to have)
Familiarity with Orleans or similar technologies for building distributed applications (nice to have)
Experience working on payment systems, payment integrations, or other high-availability, business-critical backend applications (nice to have)

Benefits

Comp & perks

Remote working arrangement with a project-based B2B engagement
Opportunity for repeat engagements based on performance and project requirements
Access to professional network insights and ongoing business support
Access to professional guidance, network connections, and relevant market insights
Possible extension after the initial 6-month assignment