You have several ways to prepare for a mobile system design interview. Some are books. Some are courses. Some are free pages. This page puts the ones I could check side by side, so you can pick what fits you.
A note first: I wrote one of these options
In short: I am the author of Mobile Design Rounds. This page is written by one of the options, so read it with that in mind.
I am Manuel Lorenzo, an Android developer. I want you to find the right resource, even when it is not mine. I do not say that any option is better or worse. I say what each one offers, what it costs on its own page, and who I think it fits.
Two tags mark every fact. Verified means I read the official page on 2026-10-14 and the link goes to it. Opinion means it is my own view. Prices change, so check the page before you pay.
The options side by side
In short: Eleven options, with price and platforms as each official page shows them on 2026-10-14. A missing price means the page did not show one.
On a phone, each row turns into a small card. A source link sits at the end of each "What it is" cell.
| Option | What it is | Price (checked 2026-10-14) | Platforms |
|---|---|---|---|
| Book and web course "Mobile System Design Interview" by Manuel Vicente Vivo, with ByteByteGo | A book announced on 2025-06-09. The web course has 11 sections: a five-step framework, seven cases (news feed, chat, stock trading, pagination library, hotel booking, Google Drive, YouTube), building blocks and a cheat sheet. Verified: course page, checked 2026-10-14 and Verified: book announcement, checked 2026-10-14 | Price not shown on either page. The Verified: pricing page, checked 2026-10-14 names plans without dollar amounts and does not say if the course is included. | The pages do not say. The author's bio is Android. |
| DesignGurus, "Grokking Modern Mobile System Design Interview" | An online course with 10 chapters, 93 lessons and about 15 hours of study. The last chapter has a lesson called a full mock interview. Verified: course page, checked 2026-10-14 | $75 one time, lifetime access. The page shows 519 learners and 4.9 from 39 ratings. | Android and iOS. The page says each lesson covers both. |
| Educative, "Grokking the Mobile System Design Interview" | An online course with 83 lessons, 101 quizzes, 18 modules, about 14 hours and 3 AI mock interviews with scoring rubrics. Verified: course page, checked 2026-10-14 | Price not shown on the page. | The page does not say. |
| System Design Handbook, mobile course on Educative | An online course with 5 modules, 80 or more lessons, 8 mock interviews and a certificate. The page does not say who runs the mocks. Verified: course page, checked 2026-10-14 | Price not listed. The page shows 1,593 learners. | The page does not say. |
| Tjeerd in 't Veen, "Mobile System Design" books | 30 chapters in three books, as PDF and ePUB, plus a quick reference guide. It includes lifetime updates and a 15-day refund. Verified: book page, checked 2026-10-14 | $89 for the bundle. | iOS, Android, Flutter and React Native. Examples use Swift, with notes for Kotlin. |
| Mahmoud Ramadan, "Cracking the Mobile System Design Interview" on Leanpub | A PDF and ePUB book with 12 chapters, including a social feed, chat, offline-first and image loading. Verified: Leanpub page, checked 2026-10-14 | $29.99 minimum, $59.99 suggested. | The subtitle says Android and iOS. |
| Hello Interview | A free guide, "System Design in a Hurry". Premium adds guided practice with feedback. Verified: guide page, checked 2026-10-14 | Premium: $47 for 1 month, $95 for 1 year, $319 for lifetime. The Verified: pricing page, checked 2026-10-14 also shows higher struck-through prices. | I found no mobile content on the pages I read. |
| Exponent, now shown as Aced | Courses that include system design, plus mock interviews and coaching with senior tech coaches, and peer mocks. The page says "formerly Exponent". Verified: course page, checked 2026-10-14 | Price not shown on the page. | I found no mobile content on the page. |
| weeeBox "mobile-system-design" on GitHub | A free written framework for mobile interviews, with a worked Twitter feed example and a link to an archive of mock interviews on YouTube. Verified: repository, checked 2026-10-14 | Free. Licence not checked. | iOS and Android. Examples use Kotlin and Room, and Swift and Core Data. |
| Company engineering blogs, for example Engineering at Meta | Free articles about real systems, with an Android category. They are not interview prep. Verified: Android category, checked 2026-10-14 | Price not checked. | Android articles on that page. |
| Mobile Design Rounds (this site) | 13 case studies written as interview answers, each with a failure table. 12 have a build guide. Three simulators and a timer. Verified: this site, checked 2026-10-14 | Free. A paid pack is only planned, and does not exist yet. | Android and iOS. |
Where the others are stronger
In short: Several options have things I do not have: people, video, brand, more topics and a long track record.
- Human feedback. Exponent says it offers mock interviews with coaches. Hello Interview Premium offers guided practice with feedback. I have no mock interviews and no human reviewer for your answers. [Opinion] A person who watches you answer is hard to replace.
- Scale and brand. ByteByteGo and DesignGurus are known brands. DesignGurus shows 519 learners on its mobile course. My site is new and has no track record.
- More topics in one place. The two big course platforms also sell backend system design. Verified: DesignGurus pricing page, checked 2026-10-14 lists several backend courses. If your loop has a backend round too, one account can cover both.
- Video and recordings. The weeeBox repository links to a YouTube archive of mock interviews. I have no video at all. I could not check any other YouTube channel, so I name none.
- Quizzes and scored practice. Educative lists 101 quizzes and 3 scored AI mock interviews. My practice tools are small simulators and a timer.
- Architecture at book length. Tjeerd in 't Veen's books run to 30 chapters. [Opinion] They fit someone who wants depth on how to organise a large app, more than a 45-minute answer.
Where Mobile Design Rounds is different
In short: It is free, covers both platforms, and writes each case as an interview answer. It is also new, with one author.
- Free. The cases and build guides cost nothing. I plan a paid pack later. It does not exist yet.
- Interview first. Each case shows the first idea, why it fails, and what to say. A failure table lists what the user sees. See the chat app failure table for an example.
- Both platforms. The Android parts follow the official Android documentation. I write the iOS parts from Apple's documentation.
- Build guides and simulators. You can read the schema and code, and then change one thing in a simulator.
- Plain English. I keep sentences short, and a script checks them before each release.
- Dated checks. Each case says what I checked in official documents and what I did not.
My limits matter as much. The site is new. One person writes it. I draft it with AI assistance and then edit and review it myself. No outside iOS engineer has reviewed the iOS parts yet. There are no mock interviews and no video.
How to choose
In short: Pick by what you lack most: feedback, depth, breadth or price.
- You want a person to judge your answers. Look at a coach-led service such as Exponent or a guided practice plan such as Hello Interview Premium. Use my timer only for solo practice.
- You have a few weeks and no budget. Start with the free options: my cases, the weeeBox repository and the free Hello Interview guide. [Opinion] Mix at least two. Then one author's blind spots do not decide your answer.
- You like quizzes and a course player. The Educative and DesignGurus courses are built that way.
- You want a book to read on your own time. Compare the ByteByteGo book, the Leanpub book and the $89 bundle. Read the sample chapters first.
- You also have a backend design round. A general system design course covers that part. None of the mobile options replace it.
- You want to see how real companies build. Read engineering blogs. They teach real systems, but they do not teach how to answer in 45 minutes.
[Opinion] Whatever you choose, practise out loud. Reading is not the same skill as answering.
What I could not verify
In short: Some things I could not check, and I left them out or marked them.
I did not find a price on the ByteByteGo, Educative, System Design Handbook or Exponent pages.
I could not load the Udemy mobile course page, so I left it out. The Stripe engineering blog showed no mobile articles in the list I read, so I left it out too. I found no ByteByteGo mobile content other than the one book and course. I did not check licences, reviews or the quality of any content. I read each page once, on one day.
Where to go next
If you chose this site, begin at Start here or read the chat app case. To see how the cases compare choices, open Compare design choices. Did you find a wrong row, a changed price or a missing option? Open an issue and I will check it and fix it.
Written by Manuel Lorenzo. The site is drafted with AI assistance and edited and reviewed by him.