Building Mobile Apps at Scale: 39 Engineering Challenges

by Gergely Orosz

While there is a lot of appreciation for backend and distributed systems challenges, there tends to be less empathy for why mobile development is hard when done at scale.

This book collects challenges engineers face when building iOS and Android apps at scale, and common ways to tackle these. By scale, we mean having numbers of users in the millions and being built by large engineering teams.

For mobile engineers, this book is a blueprint for modern app engineering approaches. For non-mobile engineers and managers, it is a resource with which to build empathy and appreciation for the complexity of world-class mobile engineering.

Genres: Programming, Technology, Nonfiction, Software, Computer Science, Engineering, Coding

217 pages, ebook

Published April 7, 2021

About the author

I wrote The Tech Resume Inside Out and I'm currently writing a book on growing as a software developer. https://blog.pragmaticengineer.com/book/

Reviews

[Yigit Yilmaz · Rating 5 out of 5]

It is a great book to comprehend all the challenges that might be relevant to mobile projects. The author covered all the topics that I saw as pain points until now in my career as a mobile engineer. It is a very comprehensive reference book not for mobile engineers but also for managers, product owners and everyone who is eager to understand the scope of mobile projects.

[Carlos Daniel · Rating 4 out of 5]

It’s an interesting journey for several important topics we need to tackle during the process of building mobile apps. All backed up by actual examples and references from Uber Engineering team.
It’s worth to read

[Divyanshu Maithani · Rating 3 out of 5]

Nicely covers a major set of challenges that people might face building medium to large scale apps. I think the book is a good start for a new mobile engineer. However for experienced engineers there isn't much new to grasp.

Each chapter is short and doesn't go in depth into possible solutions to the problems discussed. The approaches discussed are also very much scoped to Uber. Would have been nice to have some actual metrics in the chapters when talking about measurable things. The formatting is bit weird, random sponsored sections appear in between chapters.

There is very less content on cross platform frameworks like React Native and Flutter which are some of the best choices for startups starting their mobile app journey.

[Maciej Witowski · Rating 5 out of 5]

A good reference of various mobile engineering challenges and a concise starting point to dig deeper into each of them with number of links to other resources.

[Philip van den Heuvel · Rating 4 out of 5]

The book gives a very nice overview of some of the challenges faced during mobile app development. Especially from chapters 1, 2, and 5, I got a large list of ideas directly mentioned or related to the concept discussed in the book to improve the app I help to develop. The book mostly serves as a starting point for internal discussion and important points to think about, which makes it most relevant for people at the start of the middle of such a process.

[Andrea Antonioni · Rating 5 out of 5]

This book perfectly represents what are the challenges iOS and Android engineers face when working at scale on big apps with millions of users and large teams.
This is a must-read for all engineers that are curious to know more of the challenges faced by their mobile teammates.

[Darius Sabaliauskas · Rating 5 out of 5]

I think is a very good overview of mobile development and challenges.
Also, this book is full of useful tips and things to think about when scaling apps to millions of users or when building app from scratch.

[Enrique Mañas · Rating 4 out of 5]

Building Mobile Apps at Scale does a good job of summarising the state of the art of mobile development in 2021. The first half does not go too much into details, and provide a general overview of some of the technical aspects involved in mobile development. I liked more the second half, where Gergely dives deeper into real mobile development at scale (testing, modularising, organising teams, planning...), and I believe this is where the book provides value.

[Mauricio Chirino · Rating 4 out of 5]

This is one of those books that might very well work as cautionary tales (I know this for a fact since in my current job we faced ALL the pitfalls described in it).

Probably it's gonna be outdated in a couple of years as new technologies emerge but for the time being it works as a guide to sort out every major challenge known by mobile developers so far, as well as a conversation starter with those non mobile engineers.

Recommended no matter your seniority but I think It'll be specially useful for Principal and Engineer managers given the influence these roles have within their enterprises.

[Danny · Rating 5 out of 5]

As a mobile developer whose worked on a handful of large apps, this book was spot on. It offers a fantastic overview of the all the different factors and angles of mobile development, and just from a development perspective (never mind marketing, SEO, design, etc.). Highly recommend for all mobile devs, from aspiring to principles, and anyone who may work with one.

[Davor · Rating 1 out of 5]

Stay away if you aren't a novice!
Very disappointing book, I don't know why I expected more of it. In the end I just skimmed through it because it didn't give any concrete information, it just felt like a dictionary listing different technologies for mobile development.

Doesn't help at all that the book is basically a glorified ad. I have never seen in my life so many advertisements in a single book, I am honestly impressed how the author is not ashamed.
Each chapter and almost every fifth page is "sponsored" by come company.

How can you recommend KMM as the best cross-platform solution and then on the same page put an ad from a company selling KMM solutions?

Honestly, I am coming off now as a hater, but this work is a major waste of time and it feels like a student project...

[Elyamus · Rating 4 out of 5]

Since the launch of the iOS and Android app stores in 2008, the importance and impact of mobile apps has been steadily increasing. Companies are now asking their mobile teams to build more features, to do this faster, and to keep quality high but the field is relatively new and the challenges associated with building mobile apps at scale are unique, only Engineers building thick client Windows, Mac or Linux apps are the closest to relate to such difficulties; as many of these challenges are unbeknown to web or backend engineers, also very little is written about the difficulties. Gergely talks about all the challenges and how they overcame/managed them with solutions/workarounds/trade-offs during his time at Uber.

Must read for any mobile engineer that wants to level up.

[Elizabeth]

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[Mehul Kanzariya · Rating 5 out of 5]

This book shows the problems that the developers of apps with millions of users face and how the developers can prevent or solve these problems. It also lists many tools that can be useful when you're working on a large-scale app. Even if you're a developer working on a small app, you should read this book. It gives you an idea of many problems that you may be unaware of and are worth considering from day one.

[Sidnei Pereira · Rating 5 out of 5]

Great book! It summarized most of the problems in building an app. If you're building apps, it's a mandatory read. There's no deep analysis for each one, but the points will open your eyes and mind. Another great point is the many references for cases and articles in different companies and how they solve them, and it's a way for you to go deeper and solve your problem or for a better understanding.

[Ranjeet]

This is a must-read book for all Engineering Managers who come from a non-mobile background and oversimplify mobile engineering solutions. Scaling does not only mean vertical or horizontal, it can also mean scaling the process in place which can simplify the way apps are built and delivered to millions of users seamlessly. A part of the book talks about it. Read it and a lot of your misconceptions about mobile engineering will be cleared.

[Andrei Catinean · Rating 5 out of 5]

A book packed full of golden nuggets of what mobile engineering teams have to account for when building more than trivial apps. A great resource for non-mobile engineering teams and managers to understand the level of complexity your fellow "fronted mobile engineers" go through. Having worked on mobile apps at scale, I have encountered all the challenges presented by Gergeley.

[Filipe Mendes · Rating 3 out of 5]

The book goes through 39 challenges that most engineering teams face in large engineering teams and apps but that's pretty much it. Some parts seem redundant and content is often shallow but nonetheless serves as a great reference for what issues my arise whenever you decide to implement certain features.
Great read for non mobile developers, especially backend and product owners.

[Barry · Rating 4 out of 5]

Very much a breadth over depth book. It is not as technical as I was expecting. I think it does a good job of being approachable by anyone on a team, and is likely most beneficial for product owner and manager roles. Highlights the wide array of things to think about that non-mobile teams just don't have to deal with nearly as seriously.

[Jay Yeo · Rating 5 out of 5]

A collection of tacit and practical knowledge on mobile app development, with many useful links. Worth revisiting when running into the various issues covered. Big takeaway being unlike the web that's live with the latest versions, mobile app versions that are old or buggy are much harder to deal with in patching and supporting.

[Vanda · Rating 5 out of 5]

A great inspiration for anyone starting with mobile engineers, through mobile team managers, all the way to product managers.
Mobile engineers might already be familiar with some chapters, but it's still worth reading through them and rethinking how you currently approach the problematics at your work.

[Georgi Mirchev · Rating 3 out of 5]

Good for product people

This book is good for product people to manage their expectations. It gives some good explanations of how things work and what tools to use. Regarding engineering, it touches it briefly. Good for junior devs to understand how things work at large scale apps.

[Edu · Rating 5 out of 5]

This book is one-of-a-kind.

A complete and comprehensive guide of the challenges of building native apps with millions of users.
Absolutely recommended if you are serious about building apps. Or if you work with Android and iOS devs and are curious about their challenges.

[Olha · Rating 5 out of 5]

I've seen a ref to this book in this epic article: https://blog.pragmaticengineer.com/ub...
An author gave this book for free at that time.
The book is very high-level and very systematic.

[Michał Tajchert · Rating 5 out of 5]

Very good book for everybody in organization that works around mobile projects and needs a bit more details (ex. PO/SM/PM). However, if you are a mobile developer - probably 99% of things in this book will be your day-to-day work and stuff you already know.

[Jan Bjeličić · Rating 5 out of 5]

As a former iOS engineer I thoroughly enjoyed this book and learned some new things. I love the extra resources and the separation by topics that the author considered important. I'm subscribed to the pragmatic engineer newsletter and a fan overall. Keep it up with great content!

[Boris Bielik · Rating 5 out of 5]

Great rundown of non-trivial challenges that app developers hit rather sooner than later in their career.

[Dayan Ruben · Rating 5 out of 5]

Very insightful content for mobile and non-mobile engineers.

[Vander Alves · Rating 3 out of 5]

Simple, straightforward and throughout overview of the major engineering challenges faced by mobile app products aiming for usage scale and longevity.

[Dmitry · Rating 5 out of 5]

The best book of mobile architecture.