Claude API Overview and Setup
What the Claude API gives you
The Claude API lets you call Claude's models programmatically from your own app — no chat window needed. You send a request with a prompt (and optional system instructions), and get a text response back. This is the foundation for building AI-powered products: chatbots, content tools, agents, and more.
Getting your API key
Sign up at console.anthropic.com, create an API key under Settings → API Keys, and add billing details (usage is pay-as-you-go, billed per token). Never expose this key in client-side code — always call the API from a server route.
Your environment setup
Install the SDK with npm install @anthropic-ai/sdk. Store your key as ANTHROPIC_API_KEY in .env.local (never commit this file). You're now ready to make your first call.
Key Takeaways
- The Claude API is how you build AI features into your own apps.
- API keys must stay server-side — never in client code.
- Billing is per-token, pay-as-you-go.
- The official SDK simplifies request formatting and error handling.
Create your API key and environment
Sign up at console.anthropic.com, generate an API key, and add it to a new `.env.local` file in a test Next.js project as `ANTHROPIC_API_KEY=sk-ant-...`. Confirm the file is in `.gitignore`.