Java fullstack engineer

Vacant; Amsterdam; On-site; EUR 70,000 - 110,000; Full time

Job summary

Vacant is seeking a proactive software engineer to join our Identity & Access Management team as a Full-Stack Engineer. You will design, build, and scale enterprise authentication and authorization services, leveraging Java with Keycloak and microservices in Go/Kotlin, while delivering secure React-based admin interfaces.

You will work in a polyglot environment, supporting .NET SDKs and Python automation scripts, and deploying with Docker, Kubernetes, and AWS to ensure high availability and

Qualifications

• Commercial backend experience with strong Java focus in a polyglot environment (Go, Kotlin).
• Hands-on experience with identity protocols (OAuth 2.0, OpenID Connect, SAML) and Keycloak.
• Frontend capabilities with React (JS/TS) for end-to-end full-stack solutions.
• Cloud & container experience: Kubernetes, Docker, and AWS.
• SDKs and scripting: .NET and Python.
• AI-assisted development and SRE mindset for reliability and observability.

Responsibilities

• Build & scale Identity Services using Java and Keycloak; high-concurrency authorization microservices in Go/Kotlin.
• Deliver end-to-end features with React for admin dashboards and user identity journeys.
• Support polyglot ecosystems and tooling with .NET SDKs and Python automation scripts.
• Drive cloud infrastructure and reliability with Docker, Kubernetes and AWS.
• Elevate technical standards with modern security patterns (OAuth2, OIDC, RBAC/ABAC) and architectural reviews.

Skills

Java Backend

AuthN/AuthZ

React.js

Go

Kotlin

AWS

Docker

Kubernetes

Python

.NET

Tools

Keycloak

Java SDKs

Python scripting

Job description

Hungry for a challenge? Our mission? To empower every food moment around the world, whether it is through customer service, coding, or couriers.

The Opportunity:

We are looking for a proactive software engineer with a strong backend foundation and full-stack capabilities to join our Identity & Access Management (AuthN/AuthZ) team. As a Full-Stack Engineer, you will bring solid experience in security architectures, identity systems, and distributed microservices to the table. In this role, you will be instrumental in building high-throughput authorization services, extending enterprise authentication workflows, maintaining developer SDKs, and delivering intuitive frontend interfaces for our global ecosystem.

In this role you'll have the responsibility to:

• Build & Scale Identity Services: Design, develop, and maintain enterprise Authentication infrastructure built primarily on Java and Keycloak, alongside high-concurrency Authorization microservices in Go and Kotlin.
• Deliver End-to-End Features (React): Build clean, secure, and responsive frontend applications and admin dashboards using React to support seamlessly integrated user and partner identity journeys.
• Support Polyglot Ecosystems & Tooling: Support client-side .NET SDKs and write Python automation scripts to streamline developer onboarding, authorization checks, and ops automation across JET teams.
• Drive Cloud Infrastructure & Reliability: Package, deploy, and scale microservices using Docker, Kubernetes (k8s), and AWS, ensuring high availability, fault tolerance, and tight security controls.
• Elevate Technical Standards: Implement modern security patterns (OAuth2, OIDC, RBAC/ABAC), adhere to observability standards, and actively participate in collaborative architectural reviews and team knowledge sharing.

What Will You Bring to the Table?

• Solid Java Backend Experience: Commercial experience in backend engineering, with a strong primary focus on Java, and comfort working in a polyglot environment (Go, Kotlin).
• Domain Knowledge in AuthN & AuthZ: Hands-on experience with identity protocols (OAuth 2.0, OpenID Connect, SAML) and custom/open-source identity providers such as Keycloak.
• Frontend Capabilities: Nice to have hands-on proficiency or willing to work with React (JavaScript/TypeScript) to deliver modern, end-to-end full-stack solutions.
• Cloud & Container Experience: Experience operating services in production with Kubernetes (k8s), Docker, and AWS cloud services.
• SDK & Scripting Versatility: Familiarity or comfort working with .NET (for internal client SDK maintenance) and Python (for automation and tooling).
• AI-Assisted Development & SRE Mindset: Comfortable leveraging AI coding assistants to accelerate development, paired with an operational mindset focused on monitoring and reliability.

#LI-CB2