Building a Talk ChatGPT App with React Native Expo, NestJS, Google Text-to-Speech, OpenAI and TS

Press a button, talk, and hear ChatGPT answer out loud. That full voice loop is simpler than it sounds when you split it right: the React Native app converts speech to text on the device (skipping costly cloud transcription), and a NestJS backend handles OpenAI and Google Text-to-Speech, keeping your API keys off the client.

I build both sides from scratch in the video, in TypeScript.

What's inside

• Record voice and transcribe it locally to avoid speech-to-text API costs
• Send only text to a NestJS server that talks to ChatGPT
• Convert responses to MP3 with Google Text-to-Speech
• Play the audio back and replay the last message on demand
• Keep API keys server-side where they belong
• Scaffold it all with the blank TypeScript Expo template

Resources

CourseReact Native course

Backend Basics covers the server side of apps like this: 55 minutes on API routes and streaming.