Senior Software Developer Java / Kotlin

6/2021 – 4/2023

• Played primary role in the company’s successful migration from -Hyperlink entfernt- platform hosted on an in-house datacenter to the new strategic link.springer.com website hosted on Google Cloud by developing a Lua routing service and rewriting the Scala legacy monolithic application into new Kotlin services, while the applications were live and serving more than a thousand requests per second.
• Developed new APIs for nature.com, link.springer.com and biomedcentral.com websites which serve more than 5 million users daily. These APIs are both public facing as well as private with some examples being: getting a Journal, book, article, chapter by id, downloading a pdf file, checking whether the user has access to paid content (content on demand) and more.
• Liaised with other teams and business stakeholders to unify the content on demand journey and the credit deduction process of the users when they access paid content across nature.com and link.springer.com.
• Proposed as a solution, designed and implemented a rate limiting application using Redis to protect the websites from unwanted traffic which overloaded the applications and caused slower response times.

Git, Google Cloud, Java (allg.), Kotlin, Lua, Python, Scala

11/2017 – 6/2021

• Involved in a large-scale transformation project for Tesco, being part of the Price team, which consists of multiple services, accepting thousands of requests per second and serving all of the UK customers.
• Developed new APIs which have replaced legacy systems and are used for calculating all the prices, promotions, VAT, Clubcard points across Tesco and produce millions of invoices daily.
The APIs are public facing, serving the entire of Tesco across the UK handling more than 10,000 requests per second in an event driven system of strategic importance for the business in which transactions had to be immutable and idempotency had to be ensured. Examples include APIs to create a quote, add products, get the quote, accept the quote, get invoice, pay invoice, abandon the quote, claim points and more.
• Designed, implemented and supported in production end to end system solutions which provide high business value, such as allowing for automated uploading of new promotions to the Cloud system and all Tesco stores and enabling customers to retrospectively claim Clubcard points.
• Identified and resolved performance related issues.
• Closely engaged with business stakeholders to ensure business requirements are well understood so that the right solutions are implemented.
• Mentored and upskilled other engineers of the team.
• Mission critical CQRS-like system with event sourcing.
• Java 11, RxJava, Groovy, Scala for performance tests with Gatling, Vert.x, Micronaut, Kafka, AngularJS, Kubernetes (EKS and AKS), AWS (including Lambda, S3, EC2, EKS, IAM, SNS, Auto Scaling, CloudFormation and more), Azure, SQLite, Couchbase, Splunk, TDD, BDD with Cucumber, Gradle, Jenkins.
• Agile (Kanban), pair programming, daily stand ups and CI/CD with code being released automatically after it is merged.

Amazon Web Services (AWS), Java (allg.), Kafka, Kubernetes