Easy⏱️ 15-20 minutes

How to Use Claude API: Complete Beginner's Guide

Step-by-step guide to getting started with Anthropic's Claude API. From getting your API key to making your first call to building with OpenClaw.

😫 The Problem

You've used Claude on the web and love its intelligence. But the free tier has limits, the Pro subscription is $20/month, and you can't integrate Claude into your own workflows. You've heard about the API but it seems technical and intimidating. How do you actually get started?

✨ The Solution

The Claude API is surprisingly accessible. Get an API key in 5 minutes, make your first call with a simple command, and pay only for what you use (often cheaper than Pro). Better yet, use OpenClaw to handle all the API complexity for you — just chat naturally while OpenClaw manages the technical details behind the scenes.

Step by Step

Create an Anthropic account: Go to console.anthropic.com and sign up. Use your email or Google account. Verify your email address.

Add a payment method: Click on Billing in the left sidebar. Add a credit card or debit card. You'll only be charged for actual usage — there's no monthly minimum.

Get your API key: Navigate to API Keys in the console. Click 'Create Key'. Give it a descriptive name like 'personal-assistant'. Copy the key immediately — you won't see it again.

Understand the pricing: Claude API costs per token (roughly 4 characters = 1 token). Claude 3.5 Sonnet: $3 per million input tokens, $15 per million output tokens. Typical personal use: $5-20/month. Much cheaper than $20/month Pro for most users.

Test with a simple curl command: Open terminal and run: curl https://api.anthropic.com/v1/messages -H "x-api-key: YOUR_KEY" -H "content-type: application/json" -d '{"model":"claude-sonnet-4-20250514","max_tokens":1024,"messages":[{"role":"user","content":"Hello Claude!"}]}' — You should see Claude's response.

Choose how to use the API: Direct API calls (for developers), Python/Node SDK (for programmers), or OpenClaw (for everyone else). OpenClaw is the easiest path — it handles all API communication for you.

Install OpenClaw: Run 'npm install -g openclaw' in your terminal. Then run 'openclaw setup' and paste your API key when prompted. That's it — you're now using the Claude API.

Configure your model preference: In ~/.openclaw/config.yaml, you can choose between claude-sonnet-4-20250514 (fast, cheap, great for most tasks) or claude-opus-4-20250514 (most capable, more expensive). Start with Sonnet.

Start chatting: Run 'openclaw' or set up Telegram/WhatsApp integration. Every message you send goes through the Claude API, with OpenClaw adding memory, context, and action capabilities on top.

Monitor your usage: Check console.anthropic.com/usage regularly at first to understand your spending patterns. Set up usage alerts to avoid surprises.

Explore advanced features: The API supports vision (image analysis), long context windows (200K tokens), and system prompts for customization. OpenClaw exposes these through simple configuration options.

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