Building a Mobile App with OpenAI Codex (Better than Claude Code)
I built a Swift iOS app that builds apps.. a better, simpler alternative to Replit, built entirely without writing code. Using OpenAI's Codex desktop app, Xcode, and the Claude Agent SDK (Claude Code SDK), I created "Jerry" which is an iMessage style vibe coding app that generates and hosts web and mobile apps through natural conversation.
In this video, I walk through the entire process:
-designing the UI in Paper (a Figma alternative for AI agents),
-building the Swift app with Codex,
-integrating the Claude Agent SDK for AI-powered app generation,
-connecting the Vibecode CLI for hosting,
-and adding voice input with OpenAI Whisper
Tools used in this build:
OpenAI Codex (desktop coding app): https://openai.com/codex
Claude Agent SDK (Anthropic): https://docs.anthropic.com
Vibe Code CLI: https://vibecode.dev
Paper (AI-native design tool)
Xcode + Swift
OpenAI Whisper (voice input)
Where to find my other content:
https://x.com/rileybrown
/ riley-brown-7441b1101
/ realrileybrown
/ rileybrown.ai
TIME STAMPS
00:00 Intro
00:38 Why I'm Replacing Replit
01:35 The Jerry App Concept & Prompt
03:35 Setting Up Xcode & Codex
06:08 Designing the UI with Paper
10:54 First Build & Testing on iPhone
14:58 Integrating Vibe Code CLI
17:32 Testing Real App Generation
24:40 Adding Voice Input
26:44 Final Demo
#vibecoding #replitalternative #codex