Building Apps That Stick Together
Move beyond writing code to building complete systems. Learn how to connect your logic to the real world, manage data flow without the mess, and make confident architectural choices that stop decision fatigue.
Like Duolingo, but for Building Apps That Stick Together. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
170 levels across 8 sections, about 340 minutes end to end, roughly 68 days at five minutes a day. It moves through The First Mile: From Idea to Working Skeleton, Organizing the Mess: Where Does the Code Go, Data Flow: Keeping the App in Sync, Connecting to the Outside World, The Decision Matrix: Choosing Your Patterns, Refining the Experience, Shipping and Maintenance, and The Why Behind the How: Architectural Theory. It assumes you already know the basics.
Free forever · No credit card · iPhone & Android
Key ideas in Building Apps That Stick Together
- The core loop is the primary action that solves the user's main problem.
- Secondary features like profiles or social sharing don't provide the base value.
- Identifying the core loop of a specific app idea
- Building the main logic first proves the app's value immediately.
- Polishing menus and accounts too early drains energy before the app works.
- The ideal sequence of development to maintain momentum
- An MVP must be fully functional for its limited scope.
- Must-haves are essential for the app to function at all.
- The goal is to solve the primary problem, not to ship low-quality code.
- Nice-to-haves are aesthetic or convenience features that can wait.
- Splitting focus across multiple complex features leads to 'feature creep'.
- Understanding the definition of a Minimum Viable Product
- Parallel development on core features increases the risk of project abandonment.
- Distinguishing must-have features from nice-to-have features
- The loop is done when the user can complete the main action successfully.
- The consequence of building multiple core features simultaneously
You've tried the other tabs
Thirty open tabs. Four facts you actually kept.
You watched. You nodded. By Sunday it was gone.
One answer, then back to scrolling.
Eight weeks. You meant to finish. You didn't.
Tomo gives Building Apps That Stick Together the Duolingo treatment: levels, streaks, and quick quizzes that test what you just learned. That game loop is what the tabs above never had, so it's the one you actually finish.
Here's what playing it feels like
A real question from this course. Take your best guess.
If you are building a simple calculator, which of these is considered a secondary feature rather than a core requirement?
Get it right to open this lesson and 169 more in the app.
How to learn Building Apps That Stick Together, step by step
Go in order. 170 short levels across 8 sections, about 5 hours 40 minutes in all, five minutes a day.
- 1
The First Mile: From Idea to Working Skeleton
- Identifying the Core Loop: What Must Happen First
- Mapping the User's Path Without Writing Code
- Choosing Your Tech Stack Based on Constraints
- Setting Up a Clean Project Environment
- 2
Organizing the Mess: Where Does the Code Go?
- Separating What the User Sees from the Logic
- The Folder Structure That Scales with You
- Keeping Your Functions Small and Single-Purpose
- Managing Shared Variables Without Global Chaos
- When to Use Folders vs. Separate Files
- 3
Data Flow: Keeping the App in Sync
- How Information Travels Between Screens
- Storing Data Locally vs. Fetching from the Web
- Handling Loading States and Empty Screens
- 4
Connecting to the Outside World
- Talking to External Services and APIs
- Handling Errors When the Internet Fails
- Securing Your Keys and Private Information
- Parsing Complex Data into Simple Objects
- Asynchronous Tasks: Doing Two Things at Once
- 5
The Decision Matrix: Choosing Your Patterns
- The 'One Source of Truth' Pattern
- Listening for Changes: The Observer Pattern
- Using Templates to Create Repeatable Logic
- Trade-offs: Speed of Build vs. Speed of Performance
- 6
Refining the Experience
- Adding Polish with Consistent Styling
- Making Your App Accessible to Everyone
- Optimizing Images and Heavy Assets
- Feedback Loops: Buttons, Toasts, and Spinners
- Navigating Complex Screen Transitions
- Testing the Happy Path and the Edge Cases
- 7
Shipping and Maintenance
- Preparing Your App for the Real World
- Version Control: Branching for New Features
- Automating the Boring Parts of Deployment
- Monitoring Crashes and User Feedback
- 8
The Why Behind the How: Architectural Theory
- The History of Software Design Patterns
- Why Decoupling Code Saves Your Future Self
- The Philosophy of 'Don't Repeat Yourself'
8 sections · 34 units · 170 levels. Built to play, not to enroll.
Questions about Building Apps That Stick Together
How do I learn Building Apps That Stick Together?
Go in order: start with The First Mile: From Idea to Working Skeleton, then Organizing the Mess: Where Does the Code Go?, then Data Flow: Keeping the App in Sync, then Connecting to the Outside World, and 4 more sections after that. On Tomo that's 170 short levels, about 5 hours 40 minutes in all, played five minutes a day. Start free and play the first level in under a minute.
Is there a Duolingo-style app for Building Apps That Stick Together?
Yes. Tomo works like Duolingo: short daily lessons, streaks and quick quizzes. Building Apps That Stick Together is one of its free courses, and you can type any other topic to get a course of your own.
Is the Building Apps That Stick Together course free?
Yes. Building Apps That Stick Together is playable on Tomo's free plan, which doesn't expire. No credit card, no waitlist. Download the app and start your first lesson.
How long does it take to learn Building Apps That Stick Together?
170 levels across 8 sections, about 5 hours 40 minutes of play in total. It's built for five minutes a day, so you finish it a little at a time instead of all at once.
Do I need any background to start Building Apps That Stick Together?
No. It's pitched at an intermediate level, so it starts where you are and builds up. If you can tap a phone, you can start.
Tomo is in ChatGPT
Tomo is also a ChatGPT plugin: the same playable courses, built and played inside your chat.
Add Tomo to ChatGPT- What to ask
- “Make me a Tomo course on black holes.” “Turn this chat into a Tomo course.”
- What you get
- Quick questions with instant feedback, hearts and stars, ready to play in about a minute.
- Where it goes
- No sign-up to start. Connect your Tomo account and your streak carries on in the app.
You pick the voice
Building Apps That Stick Together is taught in the Professor style: clear, structured, thorough. Want a different feel? In the app you can spin up the same topic in any of Tomo's teaching styles. Same facts, totally different vibe.
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Start Building Apps That Stick Together today.
Download Tomo, search Building Apps That Stick Together, and play your first lesson in under a minute.