[Hiring] .Net Flutter Weezmo @Nayax

Role Description

Nayax is looking for a Senior Fullstack Developer (.NET + Flutter) to implement changes in the existing backend and continue the rebuild of the mobile app in Flutter. You will work across the server and mobile sides, from REST APIs to releases in the App Store and Google Play.

This role is a good fit if you can drive tasks independently across the whole stack, care about code quality, and are confident working with payment flows.

About the project: Monyx Wallet is Nayax's mobile wallet for automated businesses: vending machines, laundromats, car washes, and other self-service devices. Users pick a device by number or address, or scan a QR code, and pay from their phone. The app supports:

• Prepaid cards for closed-loop systems
• Promotions and loyalty programs
• Automatic refunds
• Branded cards
• An SDK for integration into operators' apps

Where the project is now:

• A significant part of Monyx has already been rewritten in Flutter as a standalone plugin with its own repositories.
• A new standalone Monyx app will be built on top of it in Flutter.
• Some of the logic still needs to be covered, and the payment and automatic refund flows need further work.

What you will do:

• Backend (.NET)
  • Implement changes, new features, and bug fixes in the existing backend (C#, .NET / ASP.NET Core).
  • Design, extend, and document REST APIs for the mobile app (Swagger / OpenAPI).
  • Work with relational databases: schemas, efficient queries, migrations.
  • Refactor legacy code and improve the performance, reliability, and maintainability of services.
  • Implement authentication and authorization and handle sensitive and payment data securely.
  • Write unit and integration tests and take part in code reviews.
  • Support releases, investigate production incidents, and perform root cause analysis.
• Mobile (Flutter)
  • Continue the rebuild of the mobile app in Flutter for Android and iOS.
  • Develop new screens, user flows, and reusable UI components based on design specifications.
  • Integrate the app with backend APIs: error handling, offline states, data caching.
  • Implement authentication, onboarding, deep links, push notifications, and payment flows.
  • Support localization, RTL languages (Hebrew, English), and accessibility requirements.
  • Manage state, navigation, and app architecture using clean, scalable patterns.
  • Prepare builds and publish releases to the App Store and Google Play.
• Team and process
  • Analyze requirements and user stories, estimate tasks, and propose technical solutions.
  • Use AI-assisted development tools for design, implementation, and testing, carefully reviewing code quality and security.
  • Work closely with Product Managers, designers, QA engineers, and other developers.
  • Take part in Agile ceremonies: sprint planning, backlog refinement, daily stand-ups, and retrospectives.
  • Maintain technical documentation and help improve engineering processes.
  • Share knowledge and mentor middle and junior developers.

Qualifications

• 5+ years of commercial experience building backend services in .NET and cross-platform mobile apps in Flutter.
• Experience delivering production releases for Android and iOS in Agile teams.
• Strong focus on code quality, performance, and security.

Requirements

• Backend:
  • C# and .NET (.NET 6+ / ASP.NET Core)
  • REST API design
  • Entity Framework Core and Dapper
  • SQL (MS SQL Server or PostgreSQL) with query optimization
  • OAuth 2.0 and JWT
  • Dependency Injection
  • Clean / Layered Architecture
  • SOLID principles
  • xUnit / NUnit and Moq
• Mobile:
  • Flutter and Dart (production apps for Android and iOS)
  • State management (Bloc / Riverpod / Provider)
  • REST API integration (Dio / http) and JSON serialization
  • Navigation and deep links
  • Push notifications (Firebase Cloud Messaging)
  • Localization, RTL, and accessibility
  • Local and secure storage
  • Widget and integration testing
• Tools:
  • Azure DevOps (boards, repos, pipelines)
  • Git and pull request workflow
  • Swagger / OpenAPI
  • Firebase (Crashlytics, Analytics, Cloud Messaging)
  • App Store Connect and Google Play Console
  • CI/CD for backend and mobile
• Platforms and methodologies:
  • Android, iOS, Web API / AWS cloud
  • Agile and Scrum
• Additional:
  • Code review
  • Application security basics
  • Performance optimization
  • Debugging and root cause analysis
  • Requirements analysis
  • Technical documentation

Benefits

• Work from Ukraine, fully remote.
• A work laptop is provided on request.
• Access to the Juno learning platform.
• 20 working days of vacation and sick leave.
• Medical insurance covers dental care, massages, doctor visits, and vaccinations.