As a Mobile Engineer at Scalable Capital, you will play a pivotal role in shaping the financial future of hundreds of thousands of users across Europe. Scalable Capital is a leading European neo-broker and digital wealth manager, meaning our mobile applications are the primary touchpoint for users managing their portfolios, executing trades, and setting up savings plans. The mobile engineering team is responsible for delivering a highly secure, performant, and intuitive user experience that makes complex financial operations feel effortless and accessible.

This role requires a deep understanding of mobile ecosystems—whether you specialize in Android or iOS—and a passion for clean, maintainable architecture. You will work on a product where microsecond latency, real-time data streaming, and bulletproof security are not just nice-to-haves, but core requirements. Your contributions will directly impact how users interact with stock markets, ETFs, and cryptocurrency, making your work highly visible and strategically vital to the company's growth.

The mobile team operates in a fast-paced, cross-functional environment. You will collaborate closely with product managers, UX/UI designers, and backend engineers to translate complex financial workflows into elegant mobile features. Preparing for this role means demonstrating not only your technical mastery of mobile platforms but also your ability to write scalable, testable code that can thrive in a highly regulated financial technology landscape.

The following questions are representative of what you can expect during the hiring process, compiled from real reported interview experiences at Scalable Capital. They are grouped by category to help you identify patterns and structure your preparation.

Android & Kotlin Core

This category evaluates your deep understanding of the Android platform, language-specific features in Kotlin, and native UI rendering.

• Explain the lifecycle of a custom view. How do you optimize its layout and drawing steps?
• What are the differences between AsyncTask (legacy), Kotlin Coroutines, and RxJava for background processing?

Preparing for an interview at Scalable Capital requires a balanced approach that covers technical depth, architectural knowledge, and cultural alignment. To succeed, you must demonstrate a rigorous engineering mindset and a strong sense of ownership.

Mobile Platform Mastery – You must have a deep, low-level understanding of your chosen platform (Android or iOS). Interviewers will evaluate your knowledge of native APIs, UI rendering pipelines, memory management, and performance profiling. Be prepared to explain not just how to use a tool, but how it works under the hood.

Architectural Cleanliness – Scalable Capital values clean, modular, and highly testable code. You should be ready to discuss structural patterns, dependency injection, and separation of concerns. Your ability to write code that is easy to maintain and scale is critical to their evaluation.

Problem-Solving & Resilience – The technical rounds and live coding sessions are designed to test your analytical thinking under pressure. Interviewers want to see how you break down complex requirements, handle edge cases, and respond to real-time feedback or constraints.

Culture Fit & Financial Interest – As a fintech company, Scalable Capital looks for engineers who are genuinely interested in personal finance, investing, or wealth tech. You should be able to articulate why you want to work in this domain and how your collaborative, user-focused mindset aligns with their engineering values.

The interview process at Scalable Capital is structured to evaluate your technical capabilities, architectural design skills, and cultural fit over several distinct stages. While the process is designed to be thorough, candidates should be prepared for a rigorous journey that typically spans several weeks.

The process begins with an initial screening or technical introductory call, usually led by a recruitment partner or an engineering team lead. This conversation focuses on your background, your interest in Scalable Capital, and a high-level assessment of your technical experience. If you pass this stage, you will be invited to complete a take-home technical assignment. This assignment is a cornerstone of the evaluation process, testing your ability to build a functional mobile application from scratch with a strong emphasis on clean architecture, networking, and custom UI components.

Following the submission of your assignment, you will undergo a deep-dive technical review and a live coding session. In this stage, two engineers will review your submitted code, ask you to defend your architectural choices, and potentially have you implement new features or refactor existing code live. The process concludes with a cultural fit and leadership interview, which may involve a hiring manager or executive leadership, focusing on your long-term career goals, salary alignment, and team collaboration style.

The visual timeline above outlines the standard progression of the Mobile Engineer hiring loop at Scalable Capital. Candidates should use this roadmap to pace their preparation, ensuring they allocate sufficient time to practice native UI development before receiving the take-home challenge. While the early stages move relatively quickly, the gap between stages can occasionally widen depending on team availability.

To excel in the Scalable Capital interview process, you must understand the specific areas where the engineering team places the highest emphasis. Your performance in these key domains will determine your progression through the pipeline.

Custom Views and UI Rendering

At Scalable Capital, delivering a highly polished, responsive, and unique user interface is critical. Standard platform widgets are not always sufficient for complex financial charts, interactive sliders, and custom portfolio visualizations.

Be ready to go over:

• The View Lifecycle – Detailed understanding of the measure, layout, and draw passes on Android, or layout passes and Core Animation on iOS.
• Performance Optimization – How to avoid overdraw, reduce view hierarchy depth, and ensure smooth 60fps/120fps rendering during complex animations.
• Touch Event Handling – Managing gesture detectors, intercepting touch events, and building highly interactive custom components.

Advanced concepts (less common):

• Hardware acceleration and canvas drawing.
• Custom layout managers for complex list structures.
• Implementing accessible custom views for screen readers and dynamic text.

Example scenarios:

• "Explain how you would build a custom, interactive line chart to display a user's portfolio growth over time without using third-party libraries."
• "How do you profile a laggy list view, and what steps would you take to identify the bottleneck in UI rendering?"

Data Management, Persistence, and Networking

A financial application must handle real-time data streaming, local caching, and secure transactions flawlessly. Interviewers will test your ability to build robust data layers that remain reliable under poor network conditions.

Be ready to go over:

• Local Databases – Implementing structured local storage using native frameworks like Room or Core Data without compromising UI thread performance.
• Network Resilience – Designing robust HTTP client configurations, handling connection timeouts, token refresh flows, and graceful error handling.
• State Management – Unidirectional data flow (UDF) patterns, managing loading, success, and error states cleanly across the UI.

Advanced concepts (less common):

• Offline-first synchronization strategies and conflict resolution.
• Real-time data streaming using WebSockets or Server-Sent Events (SSE).
• Custom database migrations in a production environment.

Example scenarios:

• "How would you design a repository pattern that seamlessly switches between a local database cache and a remote API depending on network availability?"
• "Describe the process of securing API communication using SSL pinning and secure storage of cryptographic keys on the device."

The Take-Home Assignment Review

The take-home assignment is where many candidacies are decided. It is not merely a pass/fail threshold; it serves as the foundation for your deep-dive technical interview.

Be ready to go over:

• Defending Design Choices – Explaining why you chose a specific architectural pattern, concurrency model, or UI structure.
• Refactoring Under Pressure – Modifying your submitted code in real-time during the live review based on new requirements provided by the interviewers.
• Testing Strategies – Demonstrating how you write unit tests for your business logic and UI tests for critical user flows.

Advanced concepts (less common):

• Mocking network responses and database states for robust integration testing.
• Managing multi-module project structures in a single repository.

Example scenarios:

• "In your submission, you chose MVVM over MVI. Can you explain the trade-offs of this decision for this specific application?"
• "Let's live-code a new feature: add a search filter to the list view you implemented in your assignment, ensuring it operates efficiently."