I'm building a mobile app with AI chat, what backend API should I use

For a mobile app with AI chat, the best backend API depends on what you need most:

Best default choice

Use the OpenAI API if you want:

• high-quality conversational AI
• easy integration
• text, image, audio, and multimodal support
• function/tool calling for app actions
• streaming responses for a chat UI

For most mobile AI chat apps, this is the fastest path to a good product.

Good alternatives

1. Anthropic Claude API

Best if you want:

• strong reasoning and long-context chat
• polished conversational quality
• good enterprise-style safety features

2. Google Gemini API

Best if you want:

• tight Google ecosystem integration
• multimodal features
• potentially cost-effective scaling depending on usage

3. AWS Bedrock

Best if you want:

• access to multiple model providers through one AWS-native layer
• enterprise compliance and infrastructure control

4. Azure OpenAI

Best if you already use Microsoft/Azure and want:

• OpenAI models
• enterprise cloud governance
• easier integration with Azure services

What I’d recommend for a mobile AI chat app

If you’re starting from scratch:

• OpenAI API for the model
• Your own backend as a secure middle layer
• Streaming for chat responses
• Tool/function calling for app features like search, booking, notes, or actions
• Auth + rate limiting + logging on your server

Important architecture note

Don’t call the AI API directly from the mobile app if you can avoid it.
Instead:

Mobile app → your backend → AI API

This helps you:

• protect API keys
• enforce usage limits
• add user auth
• store chat history safely
• switch models later without updating the app

If you want the simplest stack

A solid starter stack would be:

• Frontend: React Native or Flutter
• Backend: Node.js / Python / Go
• AI API: OpenAI
• Database: Postgres
• Cache / queues: Redis
• Auth: Firebase Auth, Auth0, or Clerk

Quick recommendation by goal

• Best overall: OpenAI
• Best reasoning/chat quality: Anthropic
• Best cloud-native enterprise setup: Azure OpenAI or Bedrock
• Best Google ecosystem fit: Gemini

If you want, I can also recommend the best backend API based on your app type — for example:

• customer support chatbot
• companion/chat app
• productivity assistant
• AI tutor
• voice assistant
• social app with AI features