Claude API — getting started

Why use the API instead of claude.ai?

Claude.ai is perfect for daily use — but the API opens a completely different level. With the API you can build your own products, automate workflows, integrate Claude into existing systems and pay only for what you use.

🏗️

Build products — integrate Claude directly into websites, apps and systems you control.

⚙️

Full control — temperature, max tokens, system prompt, model selection — everything can be controlled programmatically.

💰

Pay per use — no monthly subscription price. You pay per token in and out.

Getting started — step by step

1️⃣

Create account at console.anthropic.com and add payment information.

2️⃣

Generate API key under Settings → API Keys. Save it securely — it is only shown once.

3️⃣

Choose model — claude-sonnet-4-5 for balance between quality and price, claude-opus-4-5 for maximum quality.

API response structure

⚠️ Security:
Never store the API key directly in the code. Use environment variables (getenv) or a secrets file outside public_html — just like you do with database passwords.

"The API is not an advanced tool for experts — it is the freedom to build exactly what you want." — On the value of direct API access

🎯 Test your knowledge

Test yourself — completely optional, but fun! 🎯

Question 1 of 3

What is the most important security rule for the API key?

Never store the API key directly in the code — use environment variables or a secrets file outside public_html.

Question 2 of 3

Which Claude model is recommended for most products that balance quality and price?

claude-sonnet-4-5 gives the best balance between quality and price — recommended for most production applications.

Question 3 of 3

What is the most important advantage of the API over claude.ai for product building?

With the API you can integrate Claude directly into your own products and systems with full programmatic control over all parameters.