From junior developer to Flutter architect: the questions that come up in interviews and on real projects, answered clearly.
67 questions across 10 chapters, each tagged by level, with short answers, code where it helps, and the trade-offs that separate a good answer from a memorised one.
| Level | Who it's for |
|---|---|
| 🟢 Junior | Fundamentals every Flutter developer should know cold |
| 🟡 Senior | Trade-offs, production experience, debugging |
| 🔴 Architect | Systems, teams, risk and long-term decisions |
| # | Chapter | Questions | 🟢 | 🟡 | 🔴 |
|---|---|---|---|---|---|
| 1 | Dart essentials: null safety, the event loop, isolates, sealed classes, records, extension types | 9 | 3 | 5 | 1 |
| 2 | Flutter internals: the three trees, constraints, keys, the frame pipeline, Impeller | 8 | 3 | 4 | 1 |
| 3 | State management: ephemeral vs app state, Provider vs Riverpod vs BLoC, side effects, migrations | 7 | 2 | 3 | 2 |
| 4 | Architecture: clean architecture, feature-first folders, DI, repositories, offline, packages, ADRs | 7 | 2 | 3 | 2 |
| 5 | Performance: lists, profiling, images, raster jank, startup, app size, regressions | 7 | 2 | 4 | 1 |
| 6 | Platform integration: channels, Pigeon, FFI, Bluetooth LE, background work, plugins | 6 | 1 | 4 | 1 |
| 7 | Security: secure storage, API keys, SSL pinning, obfuscation, FinTech security | 6 | 2 | 3 | 1 |
| 8 | Testing and delivery: test types, fakes vs mocks, goldens, CI, safe releases | 6 | 1 | 4 | 1 |
| 9 | Mobile system design: feeds, chat, payments, wearable health sync, poor networks | 5 | 0 | 2 | 3 |
| 10 | Leading as an architect: wrong decisions, reviews, tech debt, disagreements, growing people | 6 | 0 | 2 | 4 |
Flutter Interview Cards turns every question here into a flashcard with spaced repetition: answer from memory, reveal the handbook's answer, and the app schedules each question again just before you'd forget it. It's free, open source (source) and keeps your progress on your device.
- Preparing for an interview? Read the chapter for your target level, then answer each question aloud before reading the answer. Being able to explain a trade-off matters more than knowing the answer.
- Leading a team? Use the 🔴 questions in architecture reviews and the 🟢 and 🟡 questions to plan what juniors learn next.
- Interviewing candidates? The answers list what a strong response covers. Look for the trade-offs, not the keywords.
- flutter-interview-cards: every question in this handbook as a spaced-repetition flashcard
- flutter-production-starter: a template app that puts chapters 3, 4, 7 and 8 into practice
- ble_gatt_parser and ble_device_simulator: parse and simulate Bluetooth LE health devices (chapter 6)
- india_validators: PAN, GSTIN, Aadhaar, IFSC and UPI validation for Indian apps
Found something wrong or out of date, or have a question that belongs here? Contributions are very welcome. See CONTRIBUTING.md. Questions and discussion go in Discussions.
If the handbook helps you, a ⭐ helps others find it.
Written by Chandra ObulaReddy, a Principal Software Engineer and Flutter architect with 8+ years of building mobile, web and cloud products used by 100K+ people, and of mentoring engineers on the way to senior and architect roles.
MIT. Share and adapt freely, with credit.