Celal Yildirim

• Lead development in the high-load distribution team, focusing on delivering scalable, reliable software solutions.
• Proficient in C# and .NET 8, specializing in building robust APIs and microservices.
• Experienced with SQL Server (MSSQL) and Entity Framework (EF) Core for efficient database management and ORM.
• Skilled in deploying and managing applications in Azure with CI/CD pipelines.
• Expertise in using Kafka for event-driven architecture, including partitioning strategies and schema management via Kafka Schema Registry.
• Implemented GraphQL for efficient, flexible service communication.
• Applied Domain-Driven Design (DDD) principles for system modeling and architecture.
• Developed and maintained comprehensive integration and unit tests to ensure code quality and system reliability.
• Strong focus on event-driven architecture, improving system scalability and performance.
• Proficient in containerizing applications with Docker for consistent development and deployment.
• Experienced in mentoring junior developers, providing constructive feedback for performance reviews, and fostering team growth.
• Held responsibility for merging code to production, with final approval on pull requests.
• Proficient in monitoring and troubleshooting using tools like New Relic, Sentry, and PagerDuty.
• Experienced in conducting 1-on-1s, participating in technical interviews, and reviewing technical assessments to ensure team growth and knowledge sharing. Delivered technical presentations in company-wide meetings and tribe demo sessions to share knowledge and showcase progress.

• Worked on vehicle-storefront squad, now working on part-exchange squad
• Main project codebase is .NET 5 & 6
• Following clean architecture on APIs, working with domains, valueObjects, entities
• Working with event driven architecture and using Kafka
• Creating abstractions top of HttpClient, Polly, Rebus, JWT, Prometheus
• Working with Rebus.Saga to handle messages
• For non GET operations the new API is designed to be fully asynchronous which means that state will be eventually consistent
• Designing and documenting systems based on results of analysis
• Using postgres on AWS, storing both saga and application databases
• Using Gitlab pipelines and running sonarqube analysis and also executing unit, smoke tests
• Writing smoke, integration and unit tests
• Worked with platform team and deployed new API on EKS with ArgoCD helm
• Helping and pair programming mid - junior developers
• Attending brainstorming meetings, creating tech debts

• Worked on checkout, logistics, subscription, payment domains
• Developed and maintained back-end applications .NET Core 3 & .NET Framework
• Refactored whole stock logic and fixed overselling stock
• Worked on new WMS project, replaced legacy WMS system with new integration, scaled in Azure Functions, used .NET 5 and Azure Service Bus as message broker
• Deployed applications on Azure, used Azure Blob Storage
• CI/CD handled by Azure DevOps
• Written medium blog post about Elastic Watcher and integration with PagerDuty
• Given tech talk about Locust load testing framework

Trendyol.com part of Alibaba Group is the largest e-commerce company in Turkey.

• Worked in Coupon & Promotion domain team
• Reduced response time by sixty percent using async architecture. Broke down monolith architecture and introduced distributed and scalable
• Replaced legacy coupon and promotion projects which were written in .NET Framework, changed to JAVA & Spring Boot
• Used RabbitMQ for messaging and built federation between RabbitMQ clusters
• Consumers were written by GO and some producers written by .NET Core
• Used DDD and TDD principles, delivered clean and testable code to meet high standard code quality
• Monitored applications using logs, grafana dashboards with higher-level and domain-oriented metrics. Used APM Tool and Open Telemetry for detailed monitoring of application
• Created deployment pipeline for new projects and enabled using Docker and Kubernetes

Hepsiburada.com is one of the largest e-commerce company in Turkey and Middle East which have 15 million active user per month.

• Developed and maintained restful API services with .NET Framework, worked on core teams and also created BFF for mobile and website
• Replaced Nancy services to .NET Core
• The new services were orchestrated by Kubernetes
• Created save-location service and saved in MongoDB, used MongoDb in-house function which is GeoJson
• Moved pipelines from GoCD to Gitlab Pipelines
• Implemented Zipkin
• Worked in 3 project as a full stack developer and used React-Redux
• Given tech talk about basic docker and react to colleagues

• Developed RESTful APIs for mobile applications with .NET Framework
• Worked on one of the project which used nosql databases and tried to associate with each other
• Deployed applications into EC2