Guides published jul 6, 2026
In this guide, you will learn how to turn an app idea into a Replit prototype you can test on your phone. The workflow is simple: define one useful user flow, give Replit Agent a focused prompt, preview with Expo Go, then improve the weakest part before adding features.
You will build a working mobile prototype called Play Day, a playlist-themed Pomodoro app. This is the example from the video guide, but the same structure works for almost any simple app idea: define the user, the job, the core screens, and the first action you want someone to test.
In the demo, Play Day takes a rough task dump like research stocks and write a blog post, turns it into Pomodoro blocks, and lets you move through the work like a playlist.
The first version is a prototype, not a production App Store release. The point is to get from idea to something testable fast enough that you can decide what to improve.
Use this workflow for any mobile idea where the first loop matters more than the full business plan. Start with one user, one job, and one believable action path. Then let Replit build the first version and test the result on your phone before adding accounts, payments, onboarding, or admin panels.
You can also turn the PRD step into a reusable prompt:
Help me write a PRD for a mobile app idea.
App idea:
[APP_IDEA]
Target user:
[TARGET_USER]
The first useful loop should be:
[FIRST_USER_ACTION]
Include:
- the core user flow
- the smallest useful set of screens
- design requirements
- features to avoid in version one
- five simple name ideas
Do not choose the tech stack. Focus on product requirements, functionality, and design direction.The bigger pattern is the part worth keeping: clarify the idea outside Replit, build the smallest useful mobile version, preview it on a real phone, then use focused Replit tasks to fix what the phone immediately exposes.
Start by signing into Replit. You can begin on a free account, but mobile app builds and AI-heavy projects can run into plan limits quickly, so use the account you actually want to build from.
Then install the Replit desktop app from replit.com/desktop (https://replit.com/desktop). In the recording, the desktop app made the workflow cleaner because Replit was not fighting for space with a pile of browser tabs. The same core flow also works from the desktop browser.
Install Expo Go on your phone before you start building. That is what lets you scan the QR code from Replit and open the generated app on a real device.
Pro tip: Treat Expo Go as the preview path, not the whole publishing process. Replit's mobile app build starts from desktop web or the desktop app, Expo Go lets you test on your phone, and App Store submission comes later through the normal Apple Developer process.
Start in ChatGPT before you open Replit. Talk through the idea until you can describe the smallest useful loop. In the video, the original idea was a broader AI scheduling app, but the stronger demo was simpler: a Pomodoro app where tasks behave like songs in a playlist.
Here is the example prompt from the video. You can use it as a fill-in-the-blanks model for your own app:
Help me write a PRD (Project Requirements Document) for a mobile app that is a playlist-themed Pomodoro timer.
The core concept is that I dictate my tasks, and the AI creates a daily playlist of everything I need to get done as Pomodoro-style sessions. If I finish a task early or get stuck, I can skip to the next item in the playlist.
Over time, the app should track my habits and use that data to help the AI:
1. Classify my tasks more accurately
2. Chunk them up effectively
3. Provide a glance at the end of the day showing exactly how long each task took
Since this is a native iOS app, we want native system support for:
1. Lock screen widgets and Live Activities
2. Push notifications
3. Dynamic Island support
Finally, please give me five ideas for a good, simple, catchy name for this app.
Once ChatGPT gives you the first draft, pick the strongest name and ask it to write the final PRD. In the video, Play Day was the best name, and the visual direction became an old-school iPod Nano style interface.
The exact app idea matters less than the shape of the prompt. Give the model a concrete concept, a simple interaction loop, design requirements, and a few naming options so you are not starting from a blank screen inside Replit.
Before you copy anything into Replit, add this instruction:
Do not choose the tech stack. Focus on the product requirements, functionality, and design direction. Let Replit decide the implementation details.That line matters. Let Replit decide how to build inside its own mobile app flow. Your PRD should explain what the app does, how it should feel, and which screens or behaviors matter most.
Open Replit on desktop and start a new build. Choose the Mobile option, then paste the final PRD into the agent chat.
Use a short command at the top:
Build me this mobile app.Then paste the PRD underneath it. This keeps Replit focused on building the prototype instead of asking it to invent the product from scratch.
In the demo, Replit initially picked up the name as Playdate instead of Play Day. Fix small naming mistakes immediately before the build goes too far:
The app is called Play Day.
While the agent works, you can use the Replit interface to check the preview, database, auth, integrations, and task board. You do not need to click through every panel manually. If the app needs an integration, API key, database, or auth setup, you can usually ask the agent to wire it up.
For a project with AI features, expect to connect an AI provider at some point. In the recording, Replit handled the AI side without extra setup, but do not assume every account or project will behave the same way.
Pro tip: Connect GitHub from Replit's integrations if you plan to keep working on the app. It gives you a normal code backup and makes it easier to bring in other agents or review changes later.
When Replit finishes the first build, look for the phone preview and QR code. Open Expo Go on your phone, scan the QR code, and give the app a minute to build the JavaScript bundle the first time.
This is the point where the workflow becomes useful. A mobile app can look fine in a simulator and still feel wrong in your hand. Test the main loop with real input.
In the demo, the test input was:
research stocks and write a blog postPlay Day turned that into multiple Pomodoro tasks:
That is the proof you are looking for. The app does not need to be finished yet. It needs to show that the core loop works well enough to keep iterating.
Once the app is on your phone, do not ask Replit to rebuild the whole thing. Create focused tasks for the problems you can actually see.
In the recording, the first issues were practical mobile problems:
Create separate Replit tasks for fixes like these:
Refactor and optimize the main screen to fit everything below the Dynamic Island and make sure it is mobile responsive.The menu at the bottom covers up some of the playlist control buttons. Make sure that does not happen and make the layout responsive.Make sure I can skip back when I am skipping through Pomodoro tasks that are not complete. Skip should mean move to the next task, not mark the task complete. Add a separate completion action if needed.Replit can run those tasks like separate branches. Each task gets its own preview, and if one overlaps with another, Replit may queue it or turn it into a subtask.
When a task turns green, review it before applying it to the main version. If the change looks right, click Apply changes to main version. If it is wrong, delete the task or ask Replit to revise it without touching the main app.
Pro tip: Replit's suggested next tasks can be useful, but do not accept them blindly. Open the suggestion, read the scope, and only keep the ones that move the prototype closer to the first real user test.
After the main prototype works, click Publish in Replit. The first publish step creates a web build on a Replit URL. You can make it public, password protected, or invite only, depending on what you are testing.
Replit may run checks during publishing, including a security scan and build steps for the Expo-based app. Let that finish before you judge the published version.
If you want to submit the app to the App Store, continue from the App Store option after the web publish step. You will need an Expo sign-in and an Apple Developer account. That part is normal App Store submission work, not something to rush through in the first 15-minute prototype pass.
The clean expectation is:
Keep going
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