(Senior) Mobile Engineer (d/f/m) - iOS & Android

Paymenttools; Köln; On-site; EUR 90,000 - 120,000; Full time

Benefits offered by this job

Flexible working hours

Language courses (English and German)

Responsibility from day one

Modern collaboration tools (Google/Con

Company events & Hackathons

Job summary

Paymenttools is hiring a (Senior) Mobile Engineer to own and evolve our mobile technology, including the WhiteLabelPay SDK used in REWE apps, and SoftPOS connected products.

You will spearhead native iOS development with Swift and collaborate across iOS and Android teams to ensure consistent APIs, stability, and a strong developer experience. Fluency in English is required; German skills are a plus.

Qualifications

• Several years of professional mobile engineering experience with extensive native iOS development.
• Deep knowledge of Apple ecosystem and modern iOS development (Swift).
• Experience developing Android applications or libraries with Kotlin and cross-platform work.
• Experience building or maintaining SDKs, libraries, or developer-facing components.
• Strong understanding of public API design, semantic versioning, and release management.
• Product-minded with focus on maintainability and long-term evolution.
• Fluent English; German skills are a plus.

Responsibilities

• Own, develop, and evolve the iOS implementation of the WhiteLabelPay SDK and future iOS apps.
• Design stable, intuitive APIs for easy customer integration.
• Work across iOS and Android to align behavior and contracts.
• Contribute to Android development and cross-platform architecture.
• Improve developer experience with documentation and tooling.
• Build mobile products beyond the SDK, including payment apps and connectors.

Skills

iOS native development

Android development

Swift

Kotlin

SDK development

Public API design

Cross-platform collaboration

English fluency

Tools

Swift

Kotlin

SDKs

iOS frameworks

Job description

(Senior) Mobile Engineer (d/f/m) - iOS & Android

Full-time

Who we are

Paymenttools is on a mission to transform the payment landscape for retailers in Europe. With more than 4.4 billion visitors per year in over 15,000 REWE Group stores and travel agencies across 21 countries, we know exactly what consumers and merchants need when exchanging goods for money. We believe in making payments seamless and invisible, linking them with value-added services within the framework of a reliable identity service. Our mantra: #wesolvepayn. We blend cutting-edge technology with stringent security to protect sensitive payment data while nurturing innovation in a cloud-native tech environment.

Who we are looking for

We’re looking for a(Senior) Mobile Engineer (d/f/m)with extensive iOS & practical Android experience to join our Mobile Team. You will help own and evolve the mobile technology at the heart of our payment ecosystem, including the WhiteLabelPay SDK used within Rewe applications , as well as mobile products such as SoftPOS applications and connectors bridging devices with the payment world.

This is more than a feature-development role. Our mobile components are integrated into products used by millions of people, so API stability, backwards compatibility, reliability, and an excellent developer experience matter enormously. You will take significant ownership of our iOS technology while also helping ensure that our Android and iOS implementations behave as one coherent product.

• Own, develop, and evolve the iOS implementation of our WhiteLabelPay SDK and future iOS applications.
• Design stable, intuitive, and developer-friendly public APIs that are easy for customers to integrate and difficult to misuse.
• Work across iOS and Android to ensure consistent behaviour, concepts, states, errors, and integration contracts between platforms.
• Contribute to Android development and architecture using Kotlin, collaborating closely with Android engineers while bringing strong cross-platform awareness.
• Improve the overall developer experience through high-quality documentation, sample applications, integration guidance, and tooling.
• Build and maintain mobile products beyond the SDK, including payment applications and components connecting mobile or IoT devices with our payment platform.
• Collaborate closely with product, engineering, architecture, customers, and other stakeholders to turn complex payment requirements into simple and reliable mobile interfaces.

Your experience

• Several years of professional mobile engineering experience, with extensive native iOS development expertise
• Deep knowledge of the Apple ecosystem and modern iOS development, ideally including Swift and commonly used iOS frameworks and architectural approaches
• Practical experience developing Android applications or libraries with Kotlin, and the ability and willingness to work across both platforms when needed
• Experience building or maintaining SDKs, libraries, frameworks, or other developer-facing platform components
• Strong understanding of public API design, semantic versioning, backwards compatibility, deprecation strategies, and release management
• A solid architecture and product mindset—you think beyond individual tickets and consider maintainability, integration experience, and long-term evolution
• Fluent English, German skills are a plus
• Experience with payment technologies, SoftPOS, security-sensitive mobile applications, or regulated environments is a strong advantage—but not required

1.000 euro annual learning and development budget + internal training platforms

Discounts on travel, fashion, technology, and more through our corporate benefits

REWE discount card for REWE group retailers

Discounted membership with EGYM Wellpass

Company provided tax services

Insurance services

Perks of working with us

Flexible working hours that fit your workflow, your time matters

Language courses (English and German)

Responsibility from day one

Work with modern and agile software such as Google Workspace, Slack, Asana, Jira, Lattice, Miro and Confluence

Company events including Hackathons and Company Days

Ask us more about these!

Not a perfect match?

We are looking forward to getting to know you, so even if you feel that you don’t quite meet all the requirements, but the position still excites you, and you think you would love to work with us, please reach out! We explicitly encourage applicants within groups that are underrepresented in tech spaces today. We value all kinds of backgrounds and walks of life.