How to use Claude API from Python in 15 lines (and why it costs $2/month)

How to use Claude API from Python in 15 lines

You don't need a $20/month subscription to use Claude. You need 15 lines of Python and $2/month.

Here's the complete working code:

import anthropic

client = anthropic.Anthropic(
    api_key="your-api-key-here"  # get from simplylouie.com/developers
)

message = client.messages.create(
    model="claude-opus-4-5",
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "Explain async/await in Python in 3 sentences."}
    ]
)

print(message.content[0].text)

That's it. That's the whole API call.

What you get back

# The response object
print(message.model)           # claude-opus-4-5
print(message.stop_reason)    # end_turn
print(message.usage.input_tokens)   # 22
print(message.usage.output_tokens)  # 87
print(message.content[0].text) # the actual answer

Add streaming (for long responses)

import anthropic

client = anthropic.Anthropic(api_key="your-api-key-here")

with client.messages.stream(
    model="claude-opus-4-5",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Write a Python function to parse CSV files."}]
) as stream:
    for text in stream.text_stream:
        print(text, end="", flush=True)

Add conversation history (multi-turn)

import anthropic

client = anthropic.Anthropic(api_key="your-api-key-here")

conversation = []

def chat(user_message):
    conversation.append({"role": "user", "content": user_message})

    response = client.messages.create(
        model="claude-opus-4-5",
        max_tokens=1024,
        messages=conversation
    )

    assistant_message = response.content[0].text
    conversation.append({"role": "assistant", "content": assistant_message})

    return assistant_message

# Use it
print(chat("What's the difference between a list and a tuple in Python?"))
print(chat("Can you show me an example of each?"))
print(chat("Which one should I use for database rows?"))

System prompts (set the AI's behavior)

import anthropic

client = anthropic.Anthropic(api_key="your-api-key-here")

response = client.messages.create(
    model="claude-opus-4-5",
    max_tokens=1024,
    system="You are a senior Python developer. Always include type hints. Always include error handling. Be concise.",
    messages=[
        {"role": "user", "content": "Write a function to read a JSON file."}
    ]
)

print(response.content[0].text)

Output:

import json
from pathlib import Path
from typing import Any

def read_json_file(file_path: str | Path) -> Any:
    """Read and parse a JSON file."""
    try:
        with open(file_path, 'r', encoding='utf-8') as f:
            return json.load(f)
    except FileNotFoundError:
        raise FileNotFoundError(f"JSON file not found: {file_path}")
    except json.JSONDecodeError as e:
        raise ValueError(f"Invalid JSON in {file_path}: {e}")

Async version (for FastAPI / async codebases)

import asyncio
import anthropic

client = anthropic.AsyncAnthropic(api_key="your-api-key-here")

async def ask_claude(question: str) -> str:
    response = await client.messages.create(
        model="claude-opus-4-5",
        max_tokens=1024,
        messages=[{"role": "user", "content": question}]
    )
    return response.content[0].text

async def main():
    answer = await ask_claude("What is the GIL in Python?")
    print(answer)

asyncio.run(main())

Install

pip install anthropic

That's the only dependency. No LangChain required. No complex setup.

The $2/month part

The Anthropic API has its own pricing (per token), but SimplyLouie offers flat-rate API access at $2/month — same Claude models, fixed cost, no token math.

For developers who don't want to track token usage: you get a standard API key, it works with the code above, and the bill is $2/month regardless of how much you use it within the fair-use limit.

# Same code, SimplyLouie key
curl https://api.simplylouie.com/v1/messages \
  -H 'Content-Type: application/json' \
  -H 'x-api-key: YOUR_SIMPLYLOUIE_KEY' \
  -d '{
    "model": "claude-opus-4-5",
    "max_tokens": 1024,
    "messages": [{"role": "user", "content": "Hello"}]
  }'

What's the actual difference between direct API and SimplyLouie?

	Anthropic Direct	SimplyLouie
Cost	~$3-15/month depending on usage	$2/month flat
Billing	Per token	Fixed monthly
Models	All Anthropic models	Claude Sonnet/Haiku
Setup	Credit card + API key	Same
Good for	High-volume production	Learning, side projects, prototypes

Quick reference

# Minimal working example
from anthropic import Anthropic
client = Anthropic(api_key="sk-...")
result = client.messages.create(
    model="claude-opus-4-5",
    max_tokens=256,
    messages=[{"role": "user", "content": "Your question here"}]
)
print(result.content[0].text)

That's the whole thing. 8 lines. The rest is optional.

---

If you're building something with Claude API and want flat-rate access without token math: simplylouie.com/developers