How to Build AI-Powered Mobile Apps Using Expo + LLM APIs in 2025

🔧 What You Need

• Node.js & Expo CLI installed
• LLM API key (OpenAI, Claude, etc.)
• Basic knowledge of JavaScript/React Native

⚙️ Step 1: Create a New Expo Project

expo init AIChatApp
cd AIChatApp
expo start

📦 Step 2: Install Required Packages

npm install axios react-native-paper

🧠 Step 3: Setup LLM API Integration

// services/aiService.js
import axios from 'axios';
const apiKey = "YOUR_OPENAI_API_KEY";

export const askAI = async (userInput) => {
  const res = await axios.post("https://api.openai.com/v1/chat/completions", {
    model: "gpt-3.5-turbo",
    messages: [{ role: "user", content: userInput }]
  }, {
    headers: {
      Authorization: `Bearer ${apiKey}`,
      "Content-Type": "application/json"
    }
  });
  return res.data.choices[0].message.content;
};

💬 Step 4: Create the Chat UI

// App.js
import React, { useState } from "react";
import { View, TextInput, Button, Text } from "react-native";
import { askAI } from "./services/aiService";

export default function App() {
  const [input, setInput] = useState("");
  const [response, setResponse] = useState("");

  const handleSubmit = async () => {
    const res = await askAI(input);
    setResponse(res);
  };

  return (
    <View>
      <TextInput value={input} onChangeText={setInput} />
      <Button title="Send to AI" onPress={handleSubmit} />
      <Text>{response}</Text>
    </View>
  );
}

🔒 Secure Your API Key

Use .env with libraries like react-native-dotenv or proxy it through your backend to hide it from clients.

🌐 Popular LLM APIs

• OpenAI GPT-4
• Anthropic Claude
• Cohere Command R+
• Google Gemini

📊 Use Case Ideas

• AI chat assistants
• AI-based productivity tools
• Voice-to-text or language translation apps
• Education & learning bots

✅ Conclusion

Building AI-powered mobile apps with Expo and LLM APIs is now easier than ever. With a few lines of code and an API key, you can build smart, intelligent apps that respond like humans. Time to create the next big thing!