Read the docs for the AI service you want to integrate. Anthropic's Claude API and OpenAI's API are the two main ones. Both have excellent documentation with code examples. The core concept is simple: you send a prompt via HTTP, you get a response back. If you've ever called a REST API, you can do this. Get your API key and make your first call with curl or Postman.

Don't build HTTP calls from scratch. Use the official SDKs — Anthropic has SDKs for Python and TypeScript, OpenAI has them for Python, Node, and more. For web apps, the Vercel AI SDK is excellent: it handles streaming, React hooks, and multiple providers out of the box. Install the SDK and you're making AI calls in 5 lines of code.

Create a backend endpoint that receives user input, calls the AI API, and returns the response. Key decisions: streaming vs. non-streaming (streaming feels faster), how to handle errors and rate limits, and how to manage conversation context. For frameworks like Next.js, the Vercel AI SDK gives you route handlers and React hooks that handle all of this.

Before going live: add input validation (prevent prompt injection), set max token limits (control costs), implement rate limiting per user, and add logging so you can debug issues. Monitor your API spend — set billing alerts in your Anthropic or OpenAI dashboard. Start with a small user group, check the logs for weird edge cases, then roll out widely.