John Roest

Software Engineer

Building systems
that last.

I'm a fullstack software engineer with nearly a decade of experience, currently working at the Netherlands Forensic Institute via Sopra Steria. I specialize in backend architecture with Java and Spring Boot, mobile development with React Native and Swift, and DevOps practices. On this blog I share what I learn along the way.

John Roest

Experience

  • Fullstack Software Engineer | Project Lead

    Nederlands Forensisch Instituut · via Sopra Steria

    Jun 2025 — Present
    • Lead a four-person engineering team while remaining hands-on in Java and Spring Boot development.
    • Act as the primary client contact, aligning technical decisions, delivery priorities and stakeholder expectations.
    • Improved the team satisfaction score from 6.4 to 8.0 by strengthening collaboration, ownership and engineering practices.
    • Design and build secure backend services for the Dutch DNA Database and PRÜM, supporting reliable DNA-profile exchange with multiple EU member states.
    • Led the greenfield design and implementation of a new backend API and established its initial architecture.
    • Introduced contract testing, reducing integration risk and increasing confidence in API changes.
    • Improved Kubernetes and OpenShift environments and introduced Docker-based local development for greater consistency.
    • Strengthened delivery through retrospectives, branching-strategy evaluation and clearer Definitions of Ready and Done.

    Tech: Java, Spring Boot, REST APIs, Kubernetes, OpenShift, Docker, CI/CD, Contract Testing, PostgreSQL, Security

  • Fullstack Software Engineer (Java, Spring Boot, Kotlin)

    Sopra Steria

    Mar 2021 — Present
    • Deliver backend functionality end-to-end using Java, Kotlin and Spring Boot, extending into React and React Native where product delivery requires it.
    • Contribute to architecture decisions for secure, business-critical systems within large organizations.
    • Translate complex business and technical requirements into maintainable software solutions.
    • Maintain engineering standards through code reviews, automated testing, CI/CD and trunk-based development.
    • Mentor engineers and help teams improve technical quality, ownership and delivery practices.
    • Collaborate with client stakeholders, product owners, designers and engineers in multidisciplinary teams.
    • Completed long-term assignments within highly regulated organizations, including the Netherlands Forensic Institute, VGZ and de Volksbank.

    Tech: Java, Kotlin, Spring Boot, REST APIs, React, React Native, CI/CD, Automated Testing, Trunk-Based Development

  • Backend & Mobile Developer

    Coöperatie VGZ · via Sopra Steria

    Nov 2021 — Jun 2025
    • Developed and maintained Java and Spring Boot APIs supporting core mobile-application functionality.
    • Designed and scaled the React Native application architecture using React Navigation, Redux Toolkit, i18n, Zod and runtime validation.
    • Advised stakeholders on Elasticsearch-based search and presented the proposed technical approach and product vision to management.
    • Built CI/CD pipelines and release automation in Azure DevOps, improving repeatability and delivery reliability.
    • Helped introduce trunk-based development, shortening feedback cycles and simplifying integration.
    • Mentored junior and medior engineers through one-to-one coaching, code reviews and pull-request feedback.
    • Collaborated across backend, mobile, product and design disciplines within a large healthcare organization.

    Tech: Java, Spring Boot, React Native, TypeScript, Elasticsearch, Azure DevOps, CI/CD, Trunk-Based Development

  • iOS App Developer

    de Volksbank · via Sopra Steria

    Sep 2021 — Dec 2021
    • Delivered user-facing iOS features end-to-end using Swift and SwiftUI.
    • Applied MVVM and clean-architecture principles to keep the application maintainable and testable.
    • Improved engineering quality through code reviews, automated testing and continuous improvement.
    • Collaborated with product and engineering stakeholders in a regulated banking environment.
    • Translated functional requirements into reliable and accessible mobile functionality.

    Tech: Swift, SwiftUI, MVVM, XCTest, Git

  • Software Developer

    MoneyMonk B.V.

    Jun 2018 — Mar 2021
    • Migrated a legacy PHP API to a modern backend built with Java, Kotlin and Spring Boot.
    • Designed and built a greenfield KYC platform using Kotlin and Spring Boot.
    • Implemented secure integrations with PSD2 banking providers, enabling automated access to financial data.
    • Owned functionality end-to-end, from solution design and backend implementation through mobile integration and release.
    • Applied clean-architecture principles to improve maintainability, stability and separation of concerns.
    • Contributed across backend, iOS and Android while helping the product and engineering organization scale.

    Tech: Java, Kotlin, Spring Boot, REST APIs, PSD2 Integrations, Swift, React, iOS, Android

  • Mobile Developer

    MoneyMonk B.V.

    Jul 2017 — Jun 2018
    • Built and released mobile features end-to-end for iOS and Android.
    • Improved application performance and stability through automated testing, code reviews and structured debugging.
    • Applied clean-architecture patterns to improve maintainability and separation of concerns.
    • Collaborated closely with backend developers, product stakeholders and designers.
    • Expanded into Kotlin and backend development, creating the foundation for progression into a fullstack role.

    Tech: Swift, Kotlin, iOS, Android, Automated Testing, Git

  • Junior Backend & iOS Developer

    MoneyMonk

    Sep 2016 — Jan 2017
    • Contributed to early Java and Spring Boot API development alongside frontend and iOS work.
    • Built responsive iOS interfaces using UIKit and RxSwift.
    • Wrote unit tests and participated in code reviews to improve software quality.
    • Collaborated with designers, testers and developers to deliver customer-facing functionality.
    • Developed a broad engineering foundation across backend, frontend and mobile development.

    Tech: Java, Spring Boot, Swift, UIKit, RxSwift, Unit Testing, Git

Technologies

KotlinJavaSwiftTypeScriptJavaScriptSpring BootReactReact NativeNode.jsNext.jsPostgreSQLMySQLDockerKubernetesElasticSearchAzure DevOpsOpenShiftAngular

Writing