Android Interview Prep · 2025–26

Everything you need to crack your next Android interview.

375 questions, real Kotlin code in every answer, and 15+ system design deep-dives — structured by topic, difficulty, and company. Everything in one place.

375+ Questions
20+ Topics
15+ System Designs
20+ Companies — Google,
Flipkart, Swiggy & more
Coroutines & Flow
Jetpack Compose
System Design
Coroutines & Flow Hard
Your checkout screen calls 3 APIs in parallel. If any one fails, cancel the rest and show an error. How do you implement this?
// ❌ Sequential — slow, no cancellation val user = fetchUser()() val cart = fetchCart()() val address = fetchAddress()()   // ✅ Parallel + fails fast on any error val (user, cart, address) = coroutineScope { val u = async { fetchUser() } val c = async { fetchCart() } val a = async { fetchAddress() } Triple(u.await(), c.await(), a.await()) }
Kotlin Language
Jetpack Compose
Coroutines & Flow
Clean Architecture
Dependency Injection
Retrofit & OkHttp
Room & DataStore
MVVM · MVI · MVP
System Design
Hilt & Dagger
Android Performance
Google · Flipkart · Swiggy
Kotlin Language
Jetpack Compose
Coroutines & Flow
Clean Architecture
Dependency Injection
Retrofit & OkHttp
Room & DataStore
MVVM · MVI · MVP
System Design
Hilt & Dagger
Android Performance
Google · Flipkart · Swiggy
Why Droidly exists
Android interviews in 2026 are deceptively hard. A topic that looks simple on the surface hides layers of nuance underneath — and with AI raising the bar for every candidate, expectations have never been higher. Most platforms treat Android as an afterthought. Generic DSA grind won't get you through a Coroutines deep-dive or an Android system design round. We built Droidly because Android developers deserve a platform built specifically for them — structured, in-depth, and focused on exactly what interviewers actually ask.
— The Droidly Team

What's new

We ship updates regularly. Here's what's been added recently.

Explore All Content →
Apr 2026
New
Micro Explainers — 30-second animated concepts
Watch Android concepts come alive: code types in, threads animate, cancellation flows. First up: Coroutines Lifecycle. Recomposition and Flow vs LiveData coming next.
Coroutines Recomposition Flow
Mar 2026
Updated
System Design — 15+ Android deep-dives
Full breakdowns with architecture decisions, data flow diagrams, Kotlin code snippets, and 20 Q&As each. Covers Chat App, Image Loader, Ride Sharing, File Downloads, Push Notifications, and more.
Chat App Image Loader Ride Sharing + 7 more
Jan 2026
Added
Company-specific question tagging
Questions now tagged by company. Know exactly what Google, Flipkart, Swiggy, PhonePe, CRED, and Zepto ask in their Android interviews — and focus there.
Google Flipkart Swiggy PhonePe
Nov 2025
Added
375+ questions — Kotlin 2.0, Android 15, Compose
Expanded question bank covering Kotlin 2.0 features, Compose stability contracts, Hilt with KSP, Android 15 APIs, and updated Coroutines patterns. Every answer has a code example.
Kotlin 2.0 Android 15 Compose Hilt KSP

375 questions across
20+ topics.

From Kotlin fundamentals to Android 15 APIs, Jetpack Compose, and architecture — all 375+ Q&A questions are free, forever. Upgrade only if you want System Design deep dives or Mock Interviews.

Open Question Bank → Sign up free · System Design & Mock Interviews are Premium
🤖
Android Domain

Activity & Fragment lifecycle, Intents, Services, Permissions, BroadcastReceivers, and 2025 APIs.

🟣
Kotlin Language

Null safety, extension functions, sealed classes, coroutines, generics, and Kotlin 2.0 features.

🎨
Jetpack Compose

Recomposition, state hoisting, side effects, custom layouts, animations, and Compose internals.

Coroutines & Flow

Suspend functions, dispatchers, StateFlow, SharedFlow, channels, and structured concurrency.

🏛️
Architecture

MVVM, MVI, Clean Architecture, multi-module apps, feature modules, and navigation patterns.

💉
Dependency Injection

Hilt, Dagger 2, component scopes, multibindings, testing with DI, and KSP migration.

🌐
Networking

Retrofit, OkHttp, interceptors, token refresh, SSL pinning, REST vs GraphQL, and gRPC.

🗄️
Data Storage

Room, DataStore, SharedPreferences, migrations, encrypted storage, and offline strategies.

🔧
Build Tools

Gradle, R8, ProGuard, APK vs AAB, build variants, flavors, and APK size reduction.

🚀
Performance

Memory leaks, overdraw, ANR, startup time, and profiling with Android Studio tools.

🏗️
Premium
System Design

Design WhatsApp, Instagram, Uber for Android. Offline sync, scalability, architecture decisions.

🤝
HR & Behavioural

STAR method answers, conflict resolution, and leadership stories for Android developer roles.

🎯
Coming Soon
Mock Interview

Personal 1:1 session with an Android engineer. Resume-based questions, real feedback, and a written report.

⌨️
Kotlin IDE
Machine Coding

Practice real interview coding problems in Kotlin — LRU cache, rate limiter, state machines, and a real Toast Android UI challenge.

Core Concepts

Understand the why, not just the what.

Deep-dive articles on the building blocks that power every Android system design answer. Conversational, analogy-driven, and packed with real code.

🧵 ~20 min read
Coroutines & Flow

From suspend functions and structured concurrency to StateFlow, SharedFlow, Channels, and back-pressure — everything you need to speak fluently about async Android.

suspend StateFlow Channel Dispatchers
🏛️ ~35 min read
MVVM Architecture

View, ViewModel, Repository, Use Cases, and Clean Architecture — with whiteboard-style diagrams, UDF explained, SavedStateHandle, Hilt wiring, and how to test each layer in isolation.

ViewModel StateFlow Repository Clean Arch
🎨 ~40 min read
Jetpack Compose

Declarative UI from the ground up — composable functions, recomposition, state hoisting, the three render phases, side effects, stability, performance, and Navigation Compose.

Recomposition State Side Effects LazyColumn
💉 ~30 min read
Dependency Injection & Hilt

Why manual construction kills testability, how Hilt's component hierarchy works, scopes explained, @Provides vs @Binds, qualifiers, and swapping real deps for fakes in tests.

Hilt @Inject Scopes Modules
♻️ ~35 min read
RecyclerView

The four recycling pools, ViewHolder pattern, DiffUtil, ListAdapter, multiple view types, ConcatAdapter, performance optimisations, and Paging 3 integration.

DiffUtil ViewHolder Paging 3 ConcatAdapter
📗 ~40 min read
Kotlin: Interview Deep Dive

Null safety, data & sealed classes, scope functions, lambdas, inline & reified, extension functions, delegation, generics, sequences, inheritance, and exceptions.

Sealed Classes Scope Functions Delegation Generics
📱 ~45 min read
Core Android Fundamentals

Activity & Fragment lifecycles, Intents, Context (Application vs Activity), Services (started/bound/foreground), Broadcast Receivers, and Content Providers.

Lifecycle Intents Services Context
🗄️ ~35 min read
Room & SQLite

WAL mode, migrations, TypeConverters, transactions, and how Room's Flow integration creates a fully reactive persistence layer without polling.

@Entity @Dao Migrations WAL
⚙️ ~40 min read
WorkManager

Constraints, chaining, idempotency, periodic work, JobScheduler, AlarmManager, and Doze mode — every background scheduling API explained and compared.

Constraints PeriodicWork Chaining AlarmManager
🌐 ~30 min read
OkHttp & Networking

Interceptors, connection pooling, certificate pinning, shadow pin rotation, caching, Retrofit wiring, and how to handle auth token refresh without race conditions.

Interceptors Cert Pinning Retrofit Caching
Micro Explainers

Learn in 30 seconds

Visual concept breakdowns — code animates in, key ideas highlight, takeaways pop. No video buffering.

▶ Auto-playing
The Process

From scattered prep
to interview-ready

Most Android devs prepare with YouTube tabs, random blogs, and hope. Droidly gives you a structured path in one place.

01
🗺️
Pick your weak spots

14 topics organised by difficulty. Start with Easy, work up to Hard. Every question is tagged by topic, level, and company — so you study what actually matters for your next interview.

Topics include Kotlin Compose Coroutines +11 more
02
💻
Study with real Kotlin code

Every single answer comes with working Kotlin code, edge cases to watch out for, and a practical interview tip. Not theory. Not pseudocode. The actual pattern your interviewer expects.

Every answer has Code snippet Edge cases Interview tip
03
🏗️
Ace system design rounds

15+ Android system design breakdowns — the round most devs fail because no one prepares for it. Design a chat app, image loader, or ride-sharing system at the senior engineer level.

Designs include Chat App Image Loader Uber Clone
04
🎯
Know your target company

Questions tagged by company. Google loves Kotlin internals and Compose. Swiggy digs into performance and offline sync. Flipkart focuses on architecture. You'll know exactly what to focus on.

Companies covered Google Flipkart Swiggy PhonePe
Real Questions

Asked at India's Top
Tech Companies

Google
42 questions
Flipkart
38 questions
Swiggy
31 questions
Zomato
28 questions
PhonePe
22 questions
CRED
19 questions
Meesho
18 questions
+12 more
Premium only
Premium Preview

See What You're
Missing Out On

🏗️ System Design Hard Asked at Google
How would you design the WhatsApp messaging architecture for Android — including offline support, message delivery receipts, and media handling?
💡 Answer

The architecture should be built around a local-first approach with SQLite (via Room) as the single source of truth. Messages are first persisted locally, then synced to the server asynchronously using a background service...

For delivery receipts, implement a 3-state system: Sent (✓), Delivered (✓✓), Read (✓✓ blue). Each state change triggers a server event that's pushed via WebSocket to the sender...

Media handling should use a chunked upload strategy with resumable uploads. Store media locally with a unique hash to avoid duplicate downloads. Use WorkManager for background uploads...

🔒
System Design — Premium

Full architecture breakdown, trade-off analysis, and interviewer evaluation criteria. Only in Premium.

Unlock for ₹299/mo →
Why Droidly

Built differently
for Android devs

Not another generic coding site. Every piece of content exists to help you clear an Android interview — nothing more, nothing less.

🎯
Android-only. No noise.

No DSA grind. No Java legacy. No generic OOP. Every question maps to what Android engineers are actually asked at Indian product companies in 2025–26.

❌ YouTube: hours of content, no structure
✅ Droidly: exactly what interviewers ask
💻
Kotlin code in every answer

Not pseudocode. Not "it depends." Real viewModelScope.launch, real @Composable, real Flow.collect — with syntax highlighting and edge cases called out.

❌ Blog posts: theory with no code
✅ Droidly: copy-pasteable Kotlin answers
🏗️
Android System Design — rare

Most platforms skip system design for Android. We have 15+ full breakdowns: Image Loader, Chat App, Offline News, Ride Sharing — each with architecture decisions, trade-offs, and 20 Q&As.

❌ LeetCode: backend system design only
✅ Droidly: mobile-first system design
📈
Mapped to rounds & difficulty

Questions tagged Easy → Medium → Hard, mapped to interview rounds. Freshers focus on Easy + Medium. Senior engineers go straight to Hard + System Design. No wasted prep time.

❌ Random articles: no difficulty signal
✅ Droidly: know exactly what to study
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HR & Behavioural section
System Design cases (15+)
Mock interview sessions
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Model answers & eval criteria
Company-wise question sets
✅ 20 companies
Completion certificate
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  • 375+ interview questions, fully unlocked
  • Code answers for every question
  • All 20+ Q&A topic categories
  • HR & Behavioural section
  • System Design cases
  • Mock interview sessions
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