Full Stack Backend Developer

Job Vacancy: Full Stack Backend Developer at KPN

We are looking for a Full Stack Backend Developer for our end client KPN.

The KPN Developer Portal Team is in search of a new, hands-on, and eager colleague! Do you have a passion for innovation and technology and are you flexible and a team player? Then read on...

About Us:

The Developer Portal team is end-to-end responsible for the distribution and delivery of developer products to KPN and its customers, suppliers, and partners. It is an international team where English is the primary language.

The entire team works two days a week from the office in Rotterdam. The team follows the Agile/Scrum methodology, values autonomy, and places great importance on trust, humor, and responsibility.

The team consists of 13 people with a wide range of expertise: front-end developers, API specialists, OPS/Infra (AWS), and backend developers.

Details:

• Start: 01-12-2025
• End: 01-06-2026
• Location: Rotterdam
• Hours: 36
• Application Deadline: 17-11 at 17:00

We look forward to hearing from you!

We are looking for someone with:

• 5+ years of professional software development experience
• Strong knowledge of OOP, clean code, SOLID principles, and design patterns
• Experience with microservices, event-driven architecture, and async messaging
• Experience with CI/CD pipelines and Infrastructure as Code (IaC)
• Good knowledge of RESTful APIs, OpenAPI/Swagger, and OAuth2
• Experience with Docker and containerized workflows
• Understanding of security best practices and observability
• A team player with ownership and strong communication skills

Tech skills:

.NET Core (C#) Stack – Must-have:

• C# 10 or higher, .NET 6–9
• ASP.NET Core Web API
• YARP
• Dependency Injection, Middleware, Filters
• Async programming
• Entity Framework Core or Dapper
• Unit and integration testing (xUnit, FluentAssertions)
• Logging, Tracing, Monitoring
• OAuth2, API versioning, rate limiting, model validation
• Knowledge of OpenAPI specification

Python / Django Stack – Must-have:

• Python 3.9+
• Django + Django REST Framework
• ORM (Django ORM or SQLAlchemy)
• Celery / Redis for background tasks
• OAuth2 authentication
• pytest / unittest
• Kubernetes
• Logging (Sentry)
• Knowledge of REST API best practices

Nice-to-have:

• Orleans (virtual actor model / grains)
• Event-driven patterns with NATS / SNS / SQS
• ClickHouse integration for analytics
• Redis caching
• ECS Fargate deployments
• AWS CDK (TypeScript) for infrastructure

AWS Cloud-native Skills:

• AWS Lambda (serverless microservices, event handlers)
• AWS ECS (Fargate) for containerized workloads
• AWS DynamoDB (partitions, indexes, TTL, stream triggers)
• AWS CDK (TypeScript) – IaC design, stacks, construct libraries
• S3, CloudWatch, IAM, API Gateway, Secrets Manager
• CloudFormation and stack deployments
• Monitoring and tracing (X-Ray, OpenTelemetry, CloudWatch Logs)
• Event-driven flows (EventBridge, SNS/SQS/NATS integration)

Data & Messaging:

• ClickHouse: query performance, schema design, materialized views
• NATS JetStream: publish/subscribe, stream management, durability
• Redis: caching and rate-limiting
• DynamoDB: schema design, partition/sort keys, secondary indexes

DevOps & Tooling:

• CI/CD pipelines (GitHub Actions, Bitbucket)
• Docker Compose/Aspire for local development
• Observability with OpenTelemetry, Serilog, Prometheus, Grafana
• Secrets management (AWS Secrets Manager / Parameter Store)
• Git, branching strategies, code reviews
• Linting, code quality tools

Soft skills:

• Ownership: taking end-to-end responsibility
• Mentoring juniors or peers
• Able to independently design, implement, and deploy features
• Strong communicator, clear code reviews
• Able to contribute technically at the architectural level

Does this sound like a match, and do you tick (a lot) of these boxes? Don’t hesitate to get in touch—we’d love to meet you!

Working Conditions

This job role offers a balanced split between operational (run) and project (build) work, with a distribution of 75% operational and 25% project-related tasks. To minimize the impact on business operations, some changes may be scheduled outside of regular business hours.

Do You Want This Too?

Do you aspire to be the best version of yourself? We are delighted to support your development and invest in an environment where continuous learning is encouraged. We provide you with the freedom to innovate and take initiative. By offering numerous growth opportunities, we help you exceed your own expectations and excel in your work, enabling you to grow both personally and professionally.

What You Can Expect

Moreover, you can expect the following benefits based on a 36 or 40-hour working week:

• An Employee Benefit Budget equivalent to 10% of your monthly income, which you can use according to your preferences. This budget allows you to purchase additional holiday days or make additional contributions to your pension.
• Flexible working hours and the possibility of location-independent work, depending on the team's planning.
• 100% reimbursement of commuting costs if you travel using public transportation. If you commute by car or motorcycle, you can opt for a commuting allowance.
• A pension scheme with a contribution rate of only 5% from your side.

Let's Get to Know Each Other

Are you the person we are looking for? The new colleague who wants to strengthen our client's team and make a difference for yourself, our customers, and society? We would love to receive your application for this vacancy.

Please Note: Even if you don't meet all the criteria mentioned in the profile, but you believe you can fulfill the role effectively, we encourage you to apply. We invest in your growth and development.

Application Process

Responses to applications are handled in accordance with our vacancy management process. If you have any questions about the application process, we will be happy to assist you via email (info@if-solutions.nl), office +31 10 210 87 90, or through the provided application link.

Screening is a standard part of the application process. We assess candidates based on the screening procedures followed by our client to ensure that new employees are reliable and suitable for their roles. For this vacancy, an individual assessment and skills testing may be included as part of the application process.

We believe that everyone is unique, and it is precisely these differences that help us become an even better bank. That's why we are curious to know more about you.