The ultimate guide to custom mobile app development

11 min read
April 18, 2023

By 2030, the mobile app market will hit a staggering $1.03 trillion.

That’s a lot of opportunity—and also plenty of competition.

If you want to enter and get a piece of this market, you must create the best custom mobile app.

This article will be your ultimate primer for custom mobile app development—what type you should go for, how much it’ll cost, and the process involved.

Types of custom mobile apps

Custom apps can be one of two types—native or cross-platform. Let’s discuss the pros and cons of each type.

Native mobile apps

A native app runs only on a single OS, either iOS or Android. It’s usually built with that platform’s specific tools and programming languages (such as Swift for iOS apps).

The best advantage of native apps is that they can take full advantage of all the platform’s built-in features and capabilities.

That means they can also run faster, manage memory better, and consume less space.

It’s also easier to tailor the user interface (UI) to fit the user’s expectations. This, in turn, helps you deliver a better user experience.

However, the trade-off is that native apps are costlier to develop overall. This is especially true if you want to develop apps for multiple operating systems.

native vs cross-platform app development costs

Source: Appinventiv

This extends into maintenance as well. Clutch estimates it takes around $10,000 to maintain an app with a development budget of just $50,000.

Cross-platform mobile apps

Cross-platform apps are developed from a single codebase written in one language. This codebase can then be compiled, optimized, and deployed for multiple platforms.

The biggest benefit is that you don’t need to write native apps individually. This saves you tons of time, money, and effort.

Plus, it’s easier to maintain a consistent look and feel across multiple apps.

Updating apps is also easier and safer. You just need to edit the main codebase, and all changes will be propagated to all app versions.

The trade-off, however, is performance. All things equal, a native app will always outperform its cross-platform counterpart. However, some approaches come close, as you can see below.

cross-platform vs native app performance

Source: Medium

There are several frameworks you can use to develop cross-platform apps. These include React Native, Xamarin, Flutter, and Apache Cordova.

Some of these have the advantage of using a widely used language (such as JavaScript), making app development easier and more accessible.

Technologies used for custom app development

There are dozens of technologies that can help you create custom apps. What you’ll use depends on the platform you’ll go for.


Android developers can use two primary languages to develop apps—Java and Kotlin. Below is a summary of their differences.

Java vs Kotlin differences

Source: Lampa

However, the good thing is that Java and Kotlin are interoperable, so you can use the two seamlessly in the same code without much issue.

Apps are developed in Android Studio, the platform’s official integrated development environment (IDE).

It contains everything developers need, including a source code editor, debugger, and a powerful automated app builder called the Gradle Build System.

Supporting these tools are several frameworks that facilitate certain aspects of Android development.

One example is Genymotion, an Android emulator that allows you to test your apps virtually in over 3,000 device types.

It’s a fantastic tool, given the severe device fragmentation inherent to Android.


Source: Genymotion

Another example is LeakCanary, a tool that detects memory issues in your Android code and finds its source.

Note that many third-party development tools and frameworks are available on Android and iOS. Examples include the mobile database Realm and the automated testing suite Appium.


The primary programming language for iOS is Swift, well-loved for its English-like syntax and relatively fast performance.

Apple’s studies claim it’s 8.4 times faster than Python, which is a similar language.

iOS development also supports two other languages—Objective-C and C++.

The former is used for legacy projects, while the latter is for more complex apps requiring fast calculations and heavy processing.

iOS’s official IDE is XCode, a comprehensive platform comparable to Android Studio.

Aside from the basics like a coding editor and debugger, XCode offers asset management features like Asset Catalog and the Assistant Editor.

Plus, it has Simulator, a powerful built-in device emulator.


Source: iClarified

Where iOS development shines, though, are the numerous frameworks and third-party tools it has.

One example is Alamofire, a networking library that makes it easy to make HTTP network calls using a few lines of code.

You can also create powerful back-ends easily with tools like Parse or Core Data. And if you’re having trouble with asynchronous programming (which is tricky), you can use RxSwift.

Cost of developing a custom mobile app

Nailing down the budget of a custom app project is perhaps one of the most challenging aspects of creating one.

The reason for this difficulty is that so many factors go into app development costs.

Let’s start with the most obvious—app complexity. It makes sense that the more features your app has, the more expensive it’ll be to create.

mobile app development cost

Source: ClustOX

The problem is that it’s difficult to quantify complexity, especially if you have an innovative feature that no one’s done before.

It’s easy to underestimate the time and money required to make it a reality.

Another factor to consider is the cost of hiring your developers.

Developer rates aren’t the same everywhere. For instance, Indian developers could charge as much as half of what an American would ask, given the same skill level.

That’s why outsourcing is a popular way to keep app costs down.

Want to develop an app for multiple platforms? That could affect your cost as well.

However, the good news is that being willing to use cross-platform frameworks instead of a native app could lower your budget.

native vs cross-platform app development cost comparison

Source: Citrusbug

Furthermore, certain requirements can increase or decrease development costs.

These can include integrating with existing systems, using certain third-party APIs, or migrating data from an older database.

For more information about custom app development costs, check out our article here.

How to develop a custom mobile app

Now, let’s look at the rough steps that need to be taken when developing a custom mobile app.

Do market research

Market research is the first and arguably most critical step in app development.

The goal here is to validate if you have a winning app idea on your hands. If it isn’t viable, you’ve just saved yourself the time and cost of creating an app that will ultimately fail.

Market research aims to evaluate your idea’s potential in two key areas (the third aspect is best left for later, before launching your app):

market research for apps

Source: App Guardians

You can gather the data you’ll need for these aspects through competitor analysis, interviews, questionnaires, and focus group discussions.

At this point, it’s worthwhile to get the services of an agency (such as DECODE) to do this step for you. It’s that important.

Create a software requirements specification

A software requirement specification (SRS) is a document that outlines all the features, objectives, functions, and requirements of your app.

In other words, it’s your app’s blueprint that helps guide all stakeholders into achieving a single vision.

Here’s what an SRS document should contain:

SRS document components

Source: Clockwise Software

Notably, it should cover both functional (what the app does) and non-functional (how the app will do it) requirements. This ensures a much clearer picture of what the app must look and feel like.

Creating an SRS requires the collaboration of everyone, including clients and developers, so that all points and problem areas are covered sufficiently.

Determine which technologies to use

It’s critical to create a technology stack that fits in with your app project’s requirements.

See, not every third-party tool, programming language, or plugin will be suitable for your project.

Each has pros, cons, and use cases that you need to consider before implementing it in your project.

tech stack structure

Source: Aimpro Soft

You must look at your SRS to find the specific technologies you need.

For instance, if a fintech app project requires top-notch security, it’s best to use an enterprise-grade programming language like Java.

You should consider other plugins like Plaid for easily connecting with other financial services.

Decide on a development methodology

The development methodology is the how of your project. It’s the framework you use to structure and plan the development process.

Like your technology stack, there are different methodologies that you can use. And each is suited for particular situations.

For example, the Scrum methodology is an approach that divides a project into iterations called sprints. Each sprint is like a mini-development process lasting anywhere from 2—4 weeks.

Scrum sprints

Source: DECODE

Scrum’s approach is great for complex projects because it ensures iterative improvement. It’s also effective at catching bugs often and early, which could lower cost and dev time.

Its opposite is the Waterfall method, where development steps are done sequentially. The main draw of this approach is simplicity, making it ideal for smaller projects.

waterfall method

Source: Adobe

Regardless of what you pick, ensure it’s the right fit, and that the whole team is comfortable with it.

Design the app’s user interface

An app’s design is one of the critical components for achieving fantastic UX. Hence, you should pay extra attention to it.

The best way to do this is to start with app wireframes as early as possible. These rough sketches let you iterate the UI design quickly, helping you arrive at a great design much sooner.

It would be best if you also used mockups and prototypes, then let end users evaluate them.

wireframe vs mockup vs prototype

Source: Aha!

You should also rely on iOS and Android design guidelines to help you create effective UIs without much guesswork.

For instance, Apple’s Human Interface Guidelines have best practices and specifications for every UI component, animation, and touch gesture.

Develop the back-end and front-end

With everything done, it’s time to write your app’s code. This will typically involve two areas—the front-end and the back-end.

frontend vs backend

Source: Flyaps

The front-end or client-side is the one that users see. This is often the app itself, including the UI and some support functions.

The back-end or server side is where most of the processing happens. For example, when you submit a form in the app, that data is sent to a server to be processed.

This is also where data can be edited or retrieved through a database.

This app development phase is crucial because it’s where you turn your plans into reality. Thus, you must have a capable dev team or hire an experienced agency like DECODE.

Perform quality assurance

Apps rarely launch without extensive testing. This process is needed to ensure that the app functions as required with as few bugs as possible.

When testing, you should implement as many methods as possible. This helps you cover every aspect of your app, from usability to performance.

Here are some methods to keep in mind.

mobile app testing types

Source: Simform

Also, don’t forget to consider automated testing tools. These can evaluate your app much more thoroughly and at a much faster rate than manual.

However, you must be careful, as qualitative tests (such as usability testing) can’t be done with automation.

Need a custom mobile app development team?

You might think that creating a custom mobile app is straightforward after reading this article.

That’s not the case at all.

In practice, there are dozens of challenges and obstacles that could get in the way. The development process is rarely smooth.

And that’s why you need a competent custom development agency like DECODE.

With dozens of apps under our belt, we have the expertise and experience to work on even the most challenging custom app project.

Interested? Get in touch with us today and schedule a free consultation.

Written by

Marko Strizic

Co-founder and CEO

Marko started DECODE with co-founders Peter and Mario, and a decade later, leads the company as CEO. His role is now almost entirely centred around business strategy, though his extensive background in software engineering makes sure he sees the future of the company from every angle. A graduate of the University of Zagreb’s Faculty of Electrical Engineering and Computing, he’s fascinated by the architecture of mobile apps and reactive programming, and a strong believer in life-long learning. Always ready for action. Or an impromptu skiing trip.

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