Zero-Code Migration: Replacing Claude API with DeepSeek

One-line Migration

DeepSeek provides an endpoint fully compatible with the Anthropic Messages API, requiring only two lines to change:

# Original code (using Claude)
import anthropic
client = anthropic.Anthropic(api_key='sk-ant-xxx')

# Migrate to DeepSeek—only change two lines!
import anthropic
client = anthropic.Anthropic(
    api_key='sk-your-deepseek-key',
    base_url='https://api.deepseek.com/anthropic'
)

# The following code remains completely unchanged!
response = client.messages.create(
    model='claude-sonnet-4-20250514',
    max_tokens=1024,
    system='You are a helpful assistant.',
    messages=[{'role': 'user', 'content': 'Hello!'}]
)
print(response.content[0].text)

Compatibility Comparison Table

Node.js Migration Example

// Migrate to DeepSeek—only change baseURL and apiKey
import Anthropic from '@anthropic-ai/sdk';
const client = new Anthropic({
  apiKey: process.env.DEEPSEEK_API_KEY,
  baseURL: 'https://api.deepseek.com/anthropic'
});

const msg = await client.messages.create({
  model: 'claude-sonnet-4-20250514',
  max_tokens: 1024,
  messages: [{ role: 'user', content: 'Explain quantum computing' }]
});
console.log(msg.content[0].text);

Typical Cost Comparison

Notes

• Model name retention: When using the Anthropic SDK, pass the Claude model name, and DeepSeek automatically maps it.
• max_tokens is required: Consistent with the Anthropic API, this parameter is mandatory.
• Response format consistency: The returned structure is exactly the same as the Anthropic API.
• Multimodal differences: DeepSeek does not support image input; ensure only text messages are sent.