Introduction
Kotlin has emerged as a modern, powerful language for Android development and beyond, offering a streamlined framework that attracts top-tier developer talent. However, the path from concept to a fully functional, scalable Kotlin application is paved with significant challenges. Many organizations find that their in-house teams, while skilled in native development, lack the specific expertise required to navigate the intricacies of Kotlin Multiplatform (KMP), manage complex library integrations, and unify logic across different operating systems. These hurdles can lead to delayed timelines, budget overruns, and a final product that falls short of its potential.
This article serves as a comprehensive guide to custom Kotlin app development. We will explore the technical and logistical difficulties teams face when building Kotlin apps in-house, from deep-rooted dependencies in legacy code to unforeseen incompatibilities in network protocols. We will then break down the costs associated with building a Kotlin app, providing clear estimates for different levels of complexity.
Most importantly, we’ll explain how partnering with a specialized agency can mitigate these risks. As a top US AI-powered app development firm with over 20 years of experience, we at MetaCTO have launched over 100 applications, helping clients build, grow, and monetize their mobile presence. We will outline how our expertise in mobile app development can help you bypass the common pitfalls of Kotlin development and deliver a high-quality, market-ready product efficiently.
What is a Kotlin app
At its core, a Kotlin app is an application built using the Kotlin programming language. Initially championed for Android development, its versatility has expanded significantly. We frequently implement systems using Kotlin for native Android applications, leveraging its modern syntax and safety features to build robust and efficient software.
Beyond native Android, the landscape of Kotlin development is largely defined by two primary approaches:
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Native Android App: This is an application built exclusively for the Android operating system. Kotlin is the officially recommended language by Google for Android development, offering full interoperability with Java and access to the entire Android SDK. This approach maximizes performance and provides seamless access to all native device features.
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Kotlin Multiplatform (KMP) App: This is a more advanced approach where Kotlin is used to write shared business logic that can run on multiple platforms, including Android, iOS, and others. The core idea is to write common code (like networking, data models, and business rules) once in a shared KMP library and then build native user interfaces (UIs) for each platform (Android and iOS). This can significantly reduce development time and cost while still allowing for a fully native user experience on each device.
A crucial aspect of building a successful Kotlin app, regardless of the approach, is its integration with a broader ecosystem of services. As part of our technology selection process at MetaCTO, we strategically consider how Kotlin integrates with essential third-party services to ensure the final product is scalable, secure, and data-driven. These integrations often include:
- Authentication: Services like Firebase to manage user sign-in and security.
- Analytics: Platforms like CleverTap to understand user behavior and drive engagement.
- Monetization: Tools like AdMob to implement revenue-generating strategies.
- Machine Learning: Services such as Azure ML to incorporate intelligent features and data processing capabilities.
By considering these integrations from the outset, we ensure that the Kotlin app is not just a standalone piece of software but a fully-featured platform ready for growth.
Reasons that it is difficult to develop a Kotlin app in house
While Kotlin offers immense potential, embarking on a Kotlin Multiplatform (KMP) project without specialized experience can expose an in-house team to a host of complex and often underestimated challenges. These difficulties span from knowledge gaps and technical debt to intricate platform-specific nuances that can derail a project.
Team Knowledge and Skill Gaps
One of the most immediate hurdles is the specialized knowledge required for KMP. On large projects, it’s common to find that almost none of the other mobile developers knew how the KMP library was created or how to work with KMP. This creates a dangerous dependency on a small number of experts, forming a knowledge silo that can slow down development, block progress, and introduce significant risk if a key team member departs. Building a cross-functional team with deep KMP expertise is a challenge, though the language’s modern, efficient framework does attract talented developers, which can enhance a company’s hiring capabilities over time.
Legacy Code and Migration Hurdles
Many companies don’t start with a blank slate. They often have an existing native Android library built long ago, and such a library may not be ready for an easy KMP migration. These legacy systems can be fraught with issues that complicate the transition, including:
- Leaking resources
- Deep-rooted context dependencies
- Widespread Java-based dependencies
Furthermore, the complexity multiplies when dealing with two separate native codebases. The effort required for wrapping two different native implementations is harder than migrating one (e.g., Android, which is already in Kotlin). Native libraries can differ significantly, causing platform-specific behaviors to leak into the common KMP interface, which undermines the goal of creating clean, shared logic.
Intricate iOS Integration Challenges
Making KMP work seamlessly with iOS is often where the most significant challenges lie. It’s not a simple plug-and-play process. Adapting iOS native code is necessary to be compatible with a KMP library. This adaptation can be surprisingly intensive. For instance, one team found that adapting the KMP MVI ViewModel for UIKit in iOS presenters took as much effort as the previous three abstraction layers combined.
The technical constraints of the iOS ecosystem add further layers of complexity:
- Single Framework Limitation: iOS has a limitation of supporting only one KMP framework per app (tracked as issue KT-42250). Overcoming this requires sophisticated workarounds, such as changing the publication format to klib, building a single bundle containing all migrated features and core code, and using this as a single framework with a unified namespace. Implementing this correctly takes significant time and often requires collaboration across different teams.
- Custom Build Tools: Standard tutorials often assume a simple project setup where a KMP framework can be added directly to Xcode. However, in a large-scale native iOS app with many modules and a custom build tool, this is often impossible. The KMP framework must be specifically adapted for the custom build tool, a task that requires deep platform-specific knowledge and assistance from the core iOS platform team.
- Build Performance: Initially, Kotlin for iOS builds was notoriously slow, which could frustrate developers and slow down iteration cycles.
Complex Network Layer Unification
The network layer is another area ripe for complications. In most large applications, the network layer is thick, containing common network request logic and specific product feature contracts. Unifying this for KMP is a major challenge for several reasons:
- Platform-Specific Contracts: Product feature contracts often differ slightly between iOS and Android. They might use different API versions or support different field lists, which complicates the creation of a single, unified network layer.
- Divergent Native Logic: The native network core logic can have significant differences. One platform might have dead features or behaviors that diverge from the other, posing a challenge for KMP unification.
- Incompatible Third-Party Libraries: The choice of networking libraries can create major roadblocks. For example, the KMP library Ktor works with the Darwin Engine on iOS, which is based on NSUrlSession. This can be incompatible with a company’s preconfigured iOS native network layers that already use a combination of NSUrlSession, the Alamofire library, and callbacks. This incompatibility may force a team to look for a way to use the Darwin Engine based on a preconfigured Alamofire instead of NSUrlSession, indicating a significant integration difficulty.
Unforeseen Protocol and Dependency Conflicts
In a large organization, communication gaps can lead to unexpected technical conflicts. A team might discover late in the process that another department, like the platform performance team, is actively researching a migration to a new protocol like HTTP/3 over QUIC. This can be a project-killer if the chosen KMP networking library, like Ktor at the time, does not support it. In that specific case, the QUIC protocol was not supported in Ktor or even directly in the native Android OkHttp library.
When faced with such a roadblock, a team may be forced to make a difficult choice. The KMP experiment couldn’t wait for QUIC support in Ktor, leading the team to use Ktor without QUIC for just a single feature and requiring a significant core logic rewrite.
Long-Term Maintenance Overhead
Even after successfully implementing a KMP library, the maintenance burden can be substantial. Supporting an adapter for native libraries after every major change in the native part would mean managing three dependent libraries (the shared KMP library, the Android native library, and the iOS native library). This interconnectedness makes maintenance difficult and increases the risk of introducing bugs with each update.
Why custom app development for Kotlin
Given the formidable challenges of in-house Kotlin development, partnering with a specialized custom app development agency is often the most strategic and efficient path forward. At MetaCTO, our entire operational model is designed to solve the very problems that can stall an internal team. We provide the expertise, processes, and holistic team structure needed to navigate the complexities of Kotlin and deliver a superior product.
Hiring an agency like us immediately resolves the critical knowledge and skill gap. Instead of relying on one or two in-house KMP experts, you gain access to an entire team that lives and breathes mobile development. We have extensive experience implementing systems using Kotlin for Android and have honed our skills in the multiplatform arena. This means we’ve already encountered and solved many of the intricate iOS integration issues, network layer unification puzzles, and build tool customizations that can derail a project.
Our expertise extends to managing and migrating legacy code. We understand that an existing native library may not be ready for a simple KMP migration. Our process involves a thorough analysis of your existing codebase to identify potential issues like resource leaks, context dependencies, and Java-based dependencies. We then develop a clear strategy for either refactoring the code for migration or wrapping it effectively, always mindful that wrapping two different native implementations is harder than migrating one. Our mobile app development services are built to handle these real-world scenarios.
Furthermore, we bring a strategic, product-focused mindset to every project. Our technology selection process is not just about picking a programming language; it’s about building a scalable ecosystem. We proactively consider how your Kotlin app will integrate with essential services for authentication (Firebase), analytics (CleverTap), monetization (AdMob), and machine learning (Azure ML). This foresight ensures your application is not only well-engineered but also poised for long-term growth and success.
Finally, a partnership with MetaCTO provides a complete, cross-functional team from day one. The cost structures for app development reflect the inclusion of not just developers but also a Business Analyst, a Scrum Master, and a QA Engineer. This integrated team approach ensures that your project is well-planned, expertly executed, and rigorously tested at every stage, preventing the communication gaps and unforeseen technical conflicts that often arise in siloed, large-scale corporate environments. We handle the complexities so you can focus on your core business.
Different types of Kotlin apps
The versatility of Kotlin allows for the development of different kinds of applications, primarily distinguished by their architecture and platform targets. The two main types are Native Android apps and Kotlin Multiplatform (KMP) apps.
Native Android Apps
A native Android app is built using Kotlin specifically and exclusively for the Android operating system. This is the most common use case for Kotlin and the one for which it was originally designed.
- Platform: Android only.
- Architecture: The entire application—from the user interface (UI) to the underlying business logic and data handling—is written in Kotlin. It has direct access to all of Google’s native APIs, libraries, and device hardware features (like the camera, GPS, and sensors).
- Benefits: This approach delivers the highest possible performance, the best user experience tailored to Android design guidelines (Material Design), and immediate access to the latest Android features as soon as they are released. We frequently implement systems using Kotlin for this purpose, creating high-performance, feature-rich Android applications.
Kotlin Multiplatform (KMP) Apps
A Kotlin Multiplatform app uses a single Kotlin codebase to share logic across multiple platforms, most commonly Android and iOS. This is not a “write once, run anywhere” solution like some cross-platform frameworks. Instead, it focuses on sharing the non-UI code while keeping the UI native to each platform.
- Platform: Android, iOS, and potentially others (desktop, web).
- Architecture: The application is divided into three parts:
- Shared KMP Module: This is where the common business logic resides. Code for networking, data storage, data models, and other platform-agnostic operations is written once in Kotlin.
- Android-Specific Module: This contains the native Android UI, written in Kotlin using Android’s native UI toolkits (like Jetpack Compose or XML layouts). It communicates with the shared KMP module for its logic and data.
- iOS-Specific Module: This contains the native iOS UI, typically written in Swift using Apple’s native UI frameworks (like SwiftUI or UIKit). It also communicates with the shared KMP module.
- Benefits: The primary advantage is code reuse, which can lead to significant cost savings. One analysis suggests that developing an app with Kotlin Multiplatform can reduce your app development cost up to 40%. It also ensures consistency in business logic across platforms, reducing the chance of bugs caused by implementing the same feature differently on Android and iOS. At the same time, it preserves a fully native look, feel, and performance for the user interface on each device.
Cost estimate for developing a Kotlin app
Understanding the financial investment required for a Kotlin app is crucial for planning and budgeting. The costs can vary significantly based on the app’s complexity, the chosen development approach (KMP vs. native), and the composition of the development team. The following estimates reflect expectations if you choose a tech partner based in Central or Eastern Europe. It’s important to note that these figures cover the work of developers, a Business Analyst, a Scrum Master, and a QA Engineer but do not include separate expenses for backend development, design, or market research.
KMP vs. Native Development Costs
Native development, using Swift for iOS and Kotlin for Android, generally has the highest costs due to the need for separate teams and codebases for each platform. Kotlin Multiplatform (KMP) offers a more cost-effective alternative by sharing a significant portion of the code, though it is still slightly more expensive than some other cross-platform options like Flutter.
| App Complexity | Kotlin Multiplatform (KMP) Cost | Native (Swift/Kotlin) Cost |
|---|---|---|
| Basic | $70,000 – $125,000 | $90,000 – $175,000 |
| Medium | $125,000 – $230,000 | $175,000 – $330,000 |
| Complex | $230,000+ | $330,000+ |
As the table shows, KMP can offer substantial savings, especially as app complexity increases. The ability to write business logic once and share it across platforms directly translates to fewer development hours.
Team Composition and Roles
The cost difference is also reflected in the team structure. KMP allows for a leaner development team.
| Development Approach | Developer Team Composition | Supporting Roles |
|---|---|---|
| Kotlin Multiplatform | 3 Developers (2 Android, 1 iOS) | QA Engineer, Business Analyst, Scrum Master |
| Native (Swift/Kotlin) | 4 Developers (2 per platform: iOS/Android) | QA Engineer, Business Analyst, Scrum Master |
Additional Service Costs
Beyond core development, most app projects require additional services to succeed. These costs are separate from the development estimates above.
| Service | Basic App Cost | Medium-Complexity App Cost | Complex App Cost |
|---|---|---|---|
| UX Research | $10,000 – $15,000 | $15,000 – $30,000 | $30,000+ |
| UI/UX Design | $20,000 – $30,000 | $30,000 – $60,000 | $60,000+ |
| Backend Development | $15,000 – $30,000 | $30,000 – $60,000 | $60,000+ |
Cost Breakdown by Role and Service
To provide a more granular view, here are the typical daily rates for key roles and monthly costs for Quality Assurance.
Daily Work-Day Costs
| Role | Cost |
|---|---|
| Native Developer | $520 / €500 |
| Designer | $520 / €500 |
| Business Analyst | $520 / €500 |
| Scrum Master | $520 / €500 |
| QA Engineer | $520 / €500 |
Monthly Quality Assurance Costs
| App Complexity | Monthly Cost | FTE (Full-Time Equivalent) |
|---|---|---|
| Basic | €2200 / $2400 | 0.25 FTE (Quarter-time) |
| Medium | €4840 / $5280 | 0.5 FTE (Half-time) |
| Complex | €9240 / $10080 | 1.0 FTE (Full-time) |
Example Project: Fintech Android App
To put these numbers into context, consider a real-world example of a Fintech Android app. The total project cost was $110,265. Here is the breakdown:
- Android App Development: $80,070
- UX/UI Design: $6,120
- QA: $12,388
- Scrum Master: $11,687
This example illustrates how different services contribute to the final cost and highlights that the development itself, while the largest component, is part of a broader set of required investments.
Top Kotlin app development companies
1. MetaCTO
When selecting a partner for your custom Kotlin app, you need a firm that combines deep technical expertise with a strategic, business-focused approach. At MetaCTO, we stand at the forefront of mobile and AI-powered application development. With over two decades of experience and more than 100 successful app launches, we have a proven track record of transforming ideas into market-leading products.
Our proficiency in Kotlin is a core component of our mobile app development practice. We frequently implement robust systems using Kotlin for Android, building applications that are not only scalable and performant but also strategically integrated with the essential services needed for growth. Our technology selection process is meticulous; we consider how Kotlin will interface with vital platforms for authentication, analytics, monetization, and machine learning, ensuring your app is built on a future-proof foundation.
What sets us apart is our holistic approach. We understand that successful app development is about more than just writing clean code. It’s about solving the complex challenges we’ve detailed throughout this guide—from navigating the intricacies of KMP and iOS integration to managing legacy systems and avoiding unforeseen technical roadblocks. Our team brings together seasoned developers, strategic business analysts, and rigorous QA engineers to provide an end-to-end solution that mitigates risk and accelerates your time to market. Whether you need to build a new application from the ground up or integrate cutting-edge capabilities through our AI Development services, we have the expertise to deliver results.
Conclusion
Kotlin offers a powerful and modern framework for building high-performance mobile applications. However, as we’ve explored, the journey of developing a custom Kotlin app, particularly with Kotlin Multiplatform, is fraught with challenges. In-house teams often grapple with significant hurdles, including specialized skill gaps, the immense difficulty of migrating legacy code, complex iOS integration issues, and the formidable task of unifying network layers across platforms. These obstacles can lead to project delays, inflated budgets, and a compromised final product.
The most effective way to navigate this complex landscape is by partnering with a specialized development agency. A custom development partner brings not only the required technical expertise but also the structured processes and integrated team needed to overcome these challenges efficiently. We’ve broken down the costs, showing that while app development is a significant investment, strategic choices like leveraging KMP can offer substantial savings over traditional native development.
At MetaCTO, we specialize in transforming your vision into a robust, scalable, and market-ready application. We provide the end-to-end expertise required to build, grow, and monetize your app, ensuring that every technical decision aligns with your business goals.
If you are ready to build your Kotlin app the right way, from day one, we invite you to connect with our team.
Talk with a Kotlin app development expert at MetaCTO.
