Claude Sonnet 4 Thinking - Starrise AI

Claude Sonnet 4 Thinking is the Extended Thinking version of Claude Sonnet 4, available through Starrise AI via OpenAI-compatible interface. Combining Sonnet’s excellent balance of speed and capability with step-by-step internal reasoning enabled by default, it significantly improves accuracy on complex tasks while maintaining fast response times.

Key Capabilities

OpenAI-compatible — Drop-in replacement for the OpenAI SDK, no other code changes needed
Extended Thinking — Step-by-step internal reasoning enabled by default
Balanced performance — Strong reasoning capability at Sonnet-level speed and cost
Advanced coding — Expert at code generation, debugging, and refactoring
Long context — Supports large document processing and multi-turn conversations
Streaming — Real-time token streaming via SSE

Quick Example

curl https://ai.alad.com/v1/messages \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4-20250514-thinking",
    "messages": [
      { "role": "user", "content": "Solve step by step: A train travels 120 km in 2 hours, then slows down and travels 80 km in 3 hours. What is the average speed for the entire journey?" }
    ]
  }'

from openai import OpenAI

client = OpenAI(
    api_key="YOUR_API_KEY",
    base_url="https://ai.alad.com/v1"
)

response = client.chat.completions.create(
    model="claude-sonnet-4-20250514-thinking",
    messages=[
        {"role": "user", "content": "Solve step by step: A train travels 120 km in 2 hours, then slows down and travels 80 km in 3 hours. What is the average speed for the entire journey?"}
    ]
)

print(response.choices[0].message.content)

from openai import OpenAI

client = OpenAI(
    api_key="YOUR_API_KEY",
    base_url="https://ai.alad.com/v1"
)

stream = client.chat.completions.create(
    model="claude-sonnet-4-20250514-thinking",
    messages=[
        {"role": "user", "content": "Prove that there are infinitely many prime numbers."}
    ],
    stream=True
)

for chunk in stream:
    print(chunk.choices[0].delta.content or "", end="")

Parameters

Parameter	Type	Required	Description
`model`	string	Yes	Fixed value: `claude-sonnet-4-20250514-thinking`
`messages`	array	Yes	Array of `{ role, content }` objects
`max_tokens`	integer	No	Maximum number of tokens to generate
`temperature`	float	No	`0`–`2`, controls randomness, default `1`
`stream`	boolean	No	Enable SSE streaming, default `false`
`top_p`	float	No	Nucleus sampling threshold, default `1`
`stop`	string / array	No	Sequences where generation stops

API Reference

View the interactive API Playground for Claude Sonnet 4 Thinking.