State-of-the-Art Coding
Optimized for HumanEval, Claude handles deep refactoring and architectural planning, ensuring consistency across large repositories and complex software environments.
claude-sonnet-4-5-20250929-thinking / web-search
Claude Sonnet 4.5 thinking code integration brings native reasoning to your workflow. This high-intelligence model from Anthropic excels at multi-file refactoring and mathematical logic with a dedicated internal thinking process for accuracy.
$ 2.4
$ 3
text
$ 12.8
$ 16
text
API
Web Search
curl --request POST "https://gptproto.com/v1/messages" \
--header "Authorization: Bearer $GPTPROTO_API_KEY" \
--header "Content-Type: application/json" \
--header "anthropic-version: 2023-06-01" \
--data '{
"model": "claude-sonnet-4-5-20250929-thinking",
"max_tokens": 1024,
"messages": [
{
"role": "user",
"content": "What'\''s the weather in NYC?"
}
],
"tools": [
{
"type": "web_search_20250305",
"name": "web_search",
"max_uses": 5
}
]
}'Claude Sonnet 4.5 Standout Features
Explore the capabilities of Claude Sonnet 4.5 thinking code, from native reasoning to industry-leading performance in coding and vision.
200k Context Support
Process massive datasets including codebases and blueprints within a 200,000 token window, maintaining high instruction adherence without losing context.
Dynamic Web Search
Enable real-time data retrieval with dynamic filtering. Claude writes code to filter search results, keeping only relevant facts and saving tokens while ensuring accuracy.
Native Chain-of-Thought
The thinking budget allows Claude to solve multi-step problems by reasoning internally before outputting a final answer, reducing logical errors in complex math queries.
How to Get a claude-sonnet-4-5-20250929-thinking API Key
Getting a claude-sonnet-4-5-20250929-thinking API key takes four steps and a few minutes. Create a free GPTProto account, add credits, generate your key, and make your first call — at $2.4 / $12.8 it's a cheaper claude-sonnet-4-5-20250929-thinking API key than going direct, and one key works across every model on the platform. Full claude-sonnet-4-5-20250929-thinking Documentation is in the docs.
Sign up
Create your free GPT Proto account to begin. You can set up an organization for your team at any time.
Top up
Your balance can be used across all models on the platform, including claude-sonnet-4-5-20250929-thinking, giving you the flexibility to experiment and scale as needed.
Generate your API key
In your dashboard, create an API key — you'll need it to authenticate when making requests to claude-sonnet-4-5-20250929-thinking.
Make your first API call
Use your API key with our sample code to send a request to claude-sonnet-4-5-20250929-thinking via GPT Proto and see instant AI-powered results.
Claude Sonnet 4.5 Thinking FAQ
Expert answers regarding Claude Sonnet 4.5 thinking code capabilities, integration steps, and reasoning parameters for developers using our platform.
What makes Claude Sonnet 4.5 thinking code unique?
Unlike the standard 3.5 variant, Claude Sonnet 4.5 Thinking adds an internal scratchpad for logical verification. This significantly improves accuracy in software engineering and complex mathematics while maintaining the 200k context window and speed expectations of the Sonnet tier.
How are thinking tokens billed for this model?
Internal reasoning tokens consumed by the Claude model are billed at the standard output rate of $15 per 1M tokens. You define the specific budget via the thinking configuration object in your request to control costs while ensuring deep logical analysis.
Does Claude Sonnet 4.5 support multimodal vision?
Yes, Claude supports images, high-density PDFs, and sampled video frames. It is particularly effective at extracting structured data from technical blueprints, financial charts, and handwritten notes by applying its internal reasoning to visual inputs.
What is the context window for 4.5 thinking?
The model features a massive 200,000-token context window, allowing for full repository ingestion or long-document analysis. It supports up to 8,192 visible output tokens, though the internal thinking budget is managed as a separate parameter within the request.
Can Claude Sonnet 4.5 search the live web?
Claude supports advanced web search tools with dynamic filtering. The model can write and execute code to post-process search results, ensuring it only ingests the most relevant data to its context window, which reduces token noise and improves accuracy.
How do I implement thinking in my API call?
To use this feature, you must include a thinking object in your JSON payload and set a budget_tokens value between 1024 and 8192. Our platform provides a 100% OpenAI-compatible header format, making it easy to migrate your existing Claude integration.
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