Claude API Has a Free Tier: Build AI Apps With the Most Capable Model

Claude isn't just a chatbot. It's an API you can build with — and Haiku at $0.80/M tokens means prototyping costs pennies.

The Claude API

Anthropic's API gives you Claude Opus 4, Sonnet 4, Haiku 3.5 — 200K context window, vision, tool use, streaming.

import anthropic
client = anthropic.Anthropic()

message = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Analyze this code for vulnerabilities..."}]
)

Tool Use

response = client.messages.create(
    model="claude-sonnet-4-20250514",
    tools=[{"name": "get_weather", "description": "Get weather", "input_schema": {"type": "object", "properties": {"location": {"type": "string"}}, "required": ["location"]}}],
    messages=[{"role": "user", "content": "Weather in Tokyo?"}]
)

Why Claude API

• 200K context — feed entire codebases (competitors: 8-32K)
• Extended thinking — better reasoning on complex tasks
• Batch API — 50% discount for non-urgent requests
• Streaming — real-time token output for UIs

Haiku $0.80/M input, Sonnet $3/M, Opus $15/M.

---

Building AI tools? Check out my data extraction toolkit or email [e-mail].