Développeur Mainframe COBOL H/F

Build the platform where Belgium feels at home.
For over 30 years, Immoweb has been more than just a platform; we are the digital heartbeat of the Belgian real estate market. From first apartments to forever homes, we bridge the gap between dreams and reality for millions of users every month.

Our mission: to inspire, guide and close every home move in Belgium. We make real estate fast, transparent, and stress-free through world-class technology and human-centric support. We are dedicated to connecting people with their property goals, ensuring that at Immoweb, your work has an immediate, nationwide impact from day one.

Your Mission
Who we are
Immoweb is Belgium's leading real estate portal, part of AVIV Group, Europe's largest network of digital real estate marketplaces. Every month, hundreds of thousands of people use our iOS app to search, save, and get alerted about the properties that matter to them. We're currently modernising our native codebase — moving from an older UIKit/MVVM stack to a leaner, more testable Swift 6 architecture — while keeping the app running reliably for our existing user base.

The Seeker squad
You'll join Seeker, a full-stack squad (iOS, Android, Web, Backend, Design) that owns the end-to-end property search and discovery experience: search, filters, saved searches and alerts, and the property detail page. We work in close collaboration with product and design, ship through CI/CD, and care about shipping quality features that scale to hundreds of thousands of daily users.

What You'll Do

• Design and build native iOS features for the Immoweb app, working closely with our Android, Web, Backend, and Design counterparts on shared feature sets.
• Contribute to our ongoing migration from UIKit/legacy patterns to SwiftUI, @Observable, and Point-Free's modular architecture libraries.
• Write clean, testable code (XCTest / Swift Testing) and review your teammates' work.
• Continuously improve app quality, performance, and stability for a large, active user base.
• Ship through our CI/CD pipeline in close collaboration with product managers.
• Be a driving force behind new features — search relevance, alerts, personalisation — and technical improvements alike.
• Share knowledge with the team and help raise the bar on iOS engineering practices across Immoweb.

What You Bring

• Solid, hands-on experience building production iOS apps in Swift, ideally including Swift 6 and iOS 18.
• Strong SwiftUI experience; comfort with @Observable and modern state management patterns.
• Good understanding of Swift Concurrency (async/await); exposure to RxSwift is a plus, as parts of our codebase are mid-migration.
• Familiarity with, or willingness to adopt, Point-Free's à la carte libraries (swift-dependencies, swift-sharing, swift-navigation, swift-case-paths).
• Experience consuming RESTful APIs; familiarity with Moya is a plus.
• A solid grasp of software architecture and Clean Architecture principles.
• Basic knowledge of unit and UI testing (XCTest / Swift Testing).
• Comfort working with Git and collaborative workflows (GitHub).
• Excellent communication skills; you're a team player who shares knowledge openly.
• English is mandatory; French or Dutch are strong assets given our Belgian market.

Nice to have

• Experience with Swift Package Manager.
• Familiarity with the Composable Architecture (TCA) or similar unidirectional architectures.
• Experience with A/B testing and product analytics/tracking.
• Experience with Bitrise or similar CI/CD tooling.
• Knowledge of accessibility best practices.
• Experience contributing to or consuming a design system.
• Familiarity with Jira and Confluence; experience working in Scrum.

What We Offer

• A friendly, quality-first engineering culture where you'll help modernise a widely-used app.
• Real ownership over features used by hundreds of thousands of people every day.
• Hybrid working, with the option to be based in Brussels or Bucharest.
• Opportunities for growth — training, conferences, and mentorship within a full-stack squad.
• The autonomy to work in the way that makes you most productive, and a say in the tools you use.