From the author of The Pragmatic Engineer and Growing as a Mobile Engineer

Building Mobile Apps at Scale: 39 Engineering Challenges

The missing guide for building large, iOS, and Android native apps -with the challenges and common solutions across the industry.

Also available as paperback, epub and on Kindle.

Building Mobile Apps at Scale
Book contributors worked at

What's Inside


1. State Management
2. Mistakes Are Hard to Revert
3. The Long Tail of Old App Versions
4. Deeplinks
5. Push and Background Notifications
6. App Crashes
7. Offline Support
8. Accessibility
9. CI/CD & The Build Train
10. Third-Party Libraries
11. Device and OS Fragmentation
12. In-App Purchases


13. Navigation Architecture Within Large Apps
14. Application State and Event-Driven Changes
15. Localization
16. Modular Architecture and Dependency Injection
17. Automated Testing
18. Manual Testing


19. Planning and Decision Making
20. Avoiding Stepping on Each Other’s Toes
21. Shared Architecture Across Several Apps
22. Tooling Maturity for Large Teams
23. Scaling Build & Merge Times
24. Mobile Platform Libraries and Teams


25. Adopting New Languages and Frameworks
26. Kotlin Multiplatform and KMM
27. Cross-Platform Feature Development
28. Cross-Platform App Development versus Native
29. Web, PWA & Backend-Driven Mobile Apps


30. Experimentation
31. Feature Flag Hell
32. Performance
33. Analytics, Monitoring and Alerting
34. Mobile On-Call
35. Advanced Code Quality Checks
36. Compliance, Privacy and Security
37. Client-Side Data Migrations
38. Forced Upgrading
39. App Size

Book Reviews

"This guide provides a rubric on how to approach scaleable engineering, something the mobile ecosystem desperately needs. Mobile engineering done at scale is so unique and complex that no one really knows where to start. "
Senior Director, Software Engineering @ Capital One
"A must-read if you are a product leader - PM, Engineer, Designer - building products at scale. Gergely does an exquisite job breaking down the why, what, and how of mobile engineering challenges at scale.
Director of Product @ Netflix
"A concise, yet comprehensive overview of the Hard Parts™ of mobile engineering. The smartphone is the pre-eminent computing device of our time — it's worth spending time familiarizing yourself with its' native challenges.
Author, The Coding Career Handbook, Formerly @Amazon & @Netlify
"I wish this book was released five years ago - then I would just hand the book over to to non-mobile managers asking why it takes so long to build a feature, and get back to app development!
Android Engineer @ Square
"Mobile apps require a totally different set of considerations compared to web applications. There is no shortage of books about building large-scale websites, but none about building large-scale mobile apps. Finally, we have a book that closes the gap.
Senior Engineering Manager, Mobile App Platform @
"An exhaustive industry survey across the globe, compiling the mobile app challenges from startups to large tech companies. A must read for anyone who wants to develop or strategize on how to build mobile apps at scale.
Mobile Architect @Halodoc

Who This Book Is For

Written for mobile engineers, engineering managers and those who want to build empathy on why it's challenging to build mobile at scale.

Native Mobile Engineers

You have experience building native iOS or Android apps. You're keen to learn about approaches and industry practices - ones you can put in place in your current project or app.

Engineering Leads and Managers

You directly or indirectly manage mobile engineers and want to stay up to date on where the industry currently is.

Stakeholders and Engineers working with Mobile Engineers

Web and backend engineers, PMs and Designers have all found this book useful in building emapthy with mobile teams.

Growing as a Mobile Engineer

Additional ebook for customers of the Full Edition version.

30 pieces of advice for mobile engineers and engineering managers.

  • 70 pages of content

  • Growing to senior and above mobile engineering levels

  • The glass ceiling for mobile engineers

  • Mobile engineering managers: advice to keep growing as a manager

  • Mobile learnings from four years at Uber

Get it as a standalone ebook


Book licenses are for personal use. See team pricing here

The ebook


  • 39 mobile engineering challenges
  • PDF, EPUB & MOBI formats & send to your Kindle
  • Growing as a Mobile Engineer ebook


  • 39 mobile engineering challenges
  • 236 pages
  • Available through Amazon
  • Kindle edition available here
  • iBooks edition available here
  • Growing as a Mobile Engineer ebook
  • *Price can vary by Amazon store


book cover


  • 39 Engineering challenges
  • 236 pages
  • Kindle version available here
  • *Price can vary by Amazon store
  • Buy on Amazon


The book was written with significant input and reviews from more than 30 experienced engineers and managers. Thank you!

Technical reviewers

Abhijith Krishnappa Halodoc
Andrea Antonioni Just Eat
Andreea Sicaru Uber
Andy Boedo RevenueCat, Elevate Labs
Ankush Gupta Quizlet
Artem Chubaryan Square
Barnabas Gema Shapr3D
Barisere Jonathan Sprinthubmobile
Corentin Kerisit Zenly
Dan Kesack DraftKings
Edu Caselles Funding Circle, author of The Mobile Interview
Emmanuel Goossaert
Franz Busch Sixt
Guillermo Orellana Monzo, Skyscanner, Badoo
Injy Zarif Convoy, Microsoft
Jake Lee Photobox
Jared Sheehan Capital One
Javi Pulido Plain Concepts
Jorge Coca VG Ventures
Julian Harty Google, eBay, Badoo, Salesforce, Klarna, ServiceNow, and others
Leland Takamine, Uber


Matija Grcic EMG Consulting
Michael Bailey GDE, American Express
Michael Sena Tesla, Amazon
Nacho Lopez Twitter, Facebook, Yahoo
Patrick Zearfoss Capital One
Praveen Sanap Carousell
Paul Razgaitis Cameo, Braintree, Venmo
Robin van Dijke Apple, Uber
Rui Peres Sphere, Babylon Health
Sabyasachi Ruj Flipkart, CloudMagic, Webyog
Sathvik Parekodi
Tuğkan Kibar
Tuomas Artman Linear, Uber
Wouter van den Broek


Gergely Orosz Uber, Microsoft, Skype, Skyscanner


Dominic Gover Best English Copy

Why is This Book Important?

Most organizations don't "get" the complexity with mobile. The book started my observation on how even "mobile-first" companies seem "backend-heavy" with their focus, with little appreciation or empathy for mobile complexity. Every mobile engineer or manager I've mentioned this to nodded, and I started writing down engineering challenges unique to native mobile engineering on large apps or large teams.

Most mobile engineers are unaware of key challenges at scale - before hitting them. I've been collecting various challenges specific to mobile for over a year - building on my 4 years experience at Uber, and 10 years of building native apps. I had a pretty complete list with 24 challenges. When I shared the draft with over 20 mobile experts, they pointed out several other areas that were common across large apps. If you are building native apps, you're more than likely to find new insights.

Buy vs build for common challenges? Mobile build systems, experimentation and feature flags, crash reporting, manual testing and several other problems you'll need to solve for regardless of your app size - what tools and solutions are commonly used in the industry? The book points to resources worth exploring.

On Social Media

Frequently Asked Questions

Can I share this book with a group?

The book license is for one reader only. Please respect the terms, and do not distribute for others. The book comes DRM-free to make your personal use easy.
Team licenses:

I'm not a mobile engineer. Is this book for me?

The primary audiance is software engineers and engineering managers building larger native iOS or Android apps. However, web and backend engineers, PMs and designers have said the book helped them build empathy when building with mobile teams.

Is there a Kindle, iBooks, or paperback version?

You can get the book as paperback here, the Kindle version here. and on iBooks here. Note that as an Amazon associate, I earn a small amount from qualifying purchases at no extra cost to you.

Where can I find the book on Goodreads?

Here it is - please consider leaving a review, once you've read the book. Thank you!


About the Author

I am an advisor at, where we are building the new standard for mobile development and write The Pragmatic Engineer (the #1 newsletter for software engineers).

I've been building native mobile apps since 2010: starting on Windows Phone, later on iOS, and Android. Starting from one person apps, I worked with small teams at Skyscanner, to hundreds of engineers working on the same codebase at Uber.

At Uber, I've been part of the Rider app rewrite, Driver app rewrite, both projects involving hundreds of mobile engineers. The apps my team worked on had 100M monthly users in 60+ countries, with several features built for a single country or region.

I’ve been working on this book - originally meant to be a blog article - on-and-off, for over a year. A Twitter post gave the final push to finish the contents off. The contents were too long for a single post. This is how this book was born.

Follow me on Twitter at @GergelyOrosz, connect on Linkedin or reach me at scale (at) pragmaticengineer (dot) com.

While I generally have a no affiliate links policy, links to my book on this page are affiliate ones, and as an Amazon Associate I earn ~4% of the revenue from qualifying purchases. This means that Amazon's 40% cut from the purchase price is reduced to around 36%.