Contents

55 chapters in three parts. 55 written so far. You have read 0 of them.

Part I. The teardown method

1	Reading apps from the outside Why does visible behavior reveal design, and where does that stop working?	Written
2	The mobile constraint set Which forces shape every mobile app, whatever it does?	Written
3	The universal app model What are the parts of any app and its backend, and which ones does this app have?	Written
4	Probes Which experiments can a user run, and what does each one expose?	Written
5	From signal to inference How do you turn an observation into a design claim, and how sure can you be?	Written
6	The teardown worksheet What does a finished teardown look like, and in what order do you fill it in?	Written

Part II. Concerns

The client core

7	Launch and startup What happens between the tap on the icon and the first useful screen?	Written
8	Navigation, deep links and screen state How does the app know where you are, how do links reach a screen, and what survives when the app is killed?	Written
9	State and UI data flow Where does each piece of on-screen data live, and what makes the screen update?	Written

Data

10	API shape How was the interface between client and backend cut, and who decides what a screen receives?	Written
11	Local storage, caching and prefetching What does the app keep on the device, what does it fetch before you ask, and when does it throw data away?	Written
12	Offline and sync What keeps working without a network, and how do the copies of data converge afterwards?	Written
13	Network transport and resilience How does the app behave on a slow, lossy or failing network, and how does it prioritize its requests?	Written
14	Real-time delivery How does new information reach the app without the user asking for it?	Written
15	Lists, feeds and pagination How does a long or endless list get loaded, ordered and kept fresh?	Written

Media

16	Images How are images sized, fetched, decoded, cached and displayed?	Written
17	Audio and video playback How does playback start fast, adapt to the network and continue in the background?	Written
18	File transfer: uploads and downloads How do large transfers survive interruptions, and who decides when they run?	Written
19	Live calls and live streaming How do audio and video move between people in real time?	Written

Trust

20	Identity and sessions How does the app know who you are, and how long does it keep believing it?	Written
21	Security and trust What does the backend refuse to trust the client with, and how is the rest protected?	Written
22	Privacy, permissions and consent What does the app ask to access, when does it ask, and what does it do when refused?	Written

The device

23	Background work and notifications What does the app do when it is not on screen, and what wakes it up?	Written
24	Location, sensors and hardware How does the app use the device's hardware, and what does that cost?	Written
25	Platform surfaces: widgets, wearables and extensions Where does the app appear outside its own window, and how do those pieces share data?	Written

The business

26	Payments and subscriptions How does money move, and which party is responsible for each step?	Written
27	Ads, attribution and growth How does the app earn from attention, and how does it know where its users came from?	Written
28	Search and discovery How does the app find things for you, and where is that work done?	Written
29	Personalization and on-device intelligence What does the app learn about you, and does the model run on the device or on the backend?	Written

Change over time

30	Remote config and experiments How does the app change its behavior without a new release?	Written
31	Server-driven UI How much of the screen does the backend decide, and how can you tell?	Written
32	UI technology: native, cross-platform and web How is each screen drawn, and what does that say about how the app is built?	Written
33	Releases and compatibility How do old versions keep working, and how are they retired?	Written

Quality

34	Observability How does the team know what the app is doing on your device?	Written
35	Performance and resource budgets How does the app spend time, battery, memory, data and storage?	Written
36	Constrained devices and networks How does the app change for cheap phones and poor networks?	Written
37	Accessibility and global reach How does the app adapt to different users, languages, regions and devices?	Written
38	Modularity, SDKs and team scale What does the app's shape tell you about the code and the organization behind it?	Written

Part III. Archetypes

Each archetype chapter is a complete worked teardown, and ends with a section on the archetype as an interview question.

39	Messaging Sync, real-time delivery, media, security	Written
40	Social feed and stories Feeds, images, personalization, caching	Written
41	Video and short-video streaming Playback, feeds, prefetching, performance	Written
42	Audio streaming and podcasts Playback, background work, downloads	Written
43	Marketplace and e-commerce Search, payments, lists, server-driven UI	Written
44	On-demand services: rides and delivery Location, real-time delivery, payments, resilience	Written
45	Booking and reservations Inventory holds, payments, consistency, offline tickets	Written
46	Banking, payments and fintech Security, sessions, compatibility, privacy	Written
47	Maps and navigation Location, offline data, performance	Written
48	Notes, documents and collaboration Sync, real-time delivery, local storage	Written
49	Meetings and calling Live calls, background work, network resilience	Written
50	AI assistants Streaming responses, on-device intelligence, sessions	Written
51	Health, fitness and connected devices Sensors, background work, sync, platform surfaces	Written
52	Games Performance, live operations, payments, ads	Written
53	Super-apps and mini-programs Modularity, server-driven UI, remote config	Written
54	Apps with no backend Local storage, hardware, performance	Written
55	The app that fits no archetype Applying the method from first principles	Written

Appendices

A	Probe catalog Every probe in the handbook, with what to watch for and where it is explained	Live
B	Teardown worksheet The fillable worksheet	Live
C	Signal index Look up an observed behavior and find the designs that produce it	Live
D	Glossary Every term the book uses, with one meaning each	Live
E	The method in a design interview How to run the teardown method forwards under a time limit	Live
F	Further reading Free and openly available sources, grouped by chapter	Live