I Built a Mobile App Using ONLY My Phone (No Laptop Required) - Replit + Expo Tutorial

Ever had an app idea while riding the bus? Instead of waiting to get home, I built the whole thing—from my phone. No laptop. No setup. Just Replit, Expo, and a few smart tools. Here's how it went, and what you can learn from it.

Tools That Made This Possible

• Replit app - A full browser-based IDE that runs on mobile
• Expo - For building and previewing React Native apps
• BrainDumper.ai - My free tool to turn rough ideas into structured app briefs
• Deepseek - AI API
• Windsurf - For App Store deployment (used only at the end)

The Exact Workflow I Followed

1. Install and open Replit on your phone

2. Use BrainDumper.ai to transform your idea into a clear project brief

3. Remix the Expo/Replit starter template

4. Run the project by hitting Play, then open the Console to preview live

5. Set a custom system prompt in the Replit Assistant:

   This is an Expo project for building React Native apps. Frame your responses accordingly.
   

6. Paste your BrainDumper context into the chat and start building

7. Debug by copying error messages into Assistant to get instant fixes

8. Connect Deepseek API to replace placeholder data with real analysis

9. Prompt Replit to improve the UI with better formatting and polish

Publishing to the App Store: Did It Work?

I attempted to run EAS Publish Preview for iOS directly from my phone... But the process failed due to mobile limitations.

So I moved to desktop for the final deployment:

• Downloaded the Replit project as a ZIP
• Opened it in Windsurf (AI IDE)
• Ran npx testflight for TestFlight deployment
• Used Cascade AI to fix errors and config issues
• Connected my Apple Developer account and uploaded to App Store Connect

Final Takeaways

What Worked Well:

• I built a real mobile app MVP entirely on my phone
• No local setup or installs needed
• Replit's Assistant + templates accelerated development
• Deepseek added working AI logic to the app

What Didn't Work:

• Publishing directly from mobile was clunky and unreliable
• A few bugs and edge cases required desktop-level debugging

🤔 Should You Try This?

If you want to quickly prototype mobile apps or test ideas on the go, this workflow is amazing. You can go from nothing → MVP in under an hour, without a laptop.

Pro Tip: If you're planning to publish to the App Store or handle backend logic, you'll likely need to finish on a desktop. But for rapid prototyping and initial development, this mobile-first approach is surprisingly effective!