Claude Sonnet 4.5

Claude Sonnet 4.5 is Anthropic’s most advanced Sonnet model to date, optimized for real-world agents and coding workflows. It delivers state-of-the-art performance on coding benchmarks such as SWE-bench Verified, with improvements across system design, code security, and specification adherence. The model is designed for extended autonomous operation, maintaining task continuity across sessions and providing fact-based progress tracking. Sonnet 4.5 also introduces stronger agentic capabilities, including improved tool orchestration, speculative parallel execution, and more efficient context and memory management. With enhanced context tracking and awareness of token usage across tool calls, it is particularly well-suited for multi-context and long-running workflows. Use cases span software engineering, cybersecurity, financial analysis, research agents, and other domains requiring sustained reasoning and tool use.

ChatAnthropic1M tokens$3.2702 / $16.3509 · 1M

anthropic/claude-sonnet-4.5

Context
1M tokens
Completion cap
64,000
Tools
Yes
JSON
Yes
Released
2025-09-29

Call it from Geek Hub

Same OpenAI SDK. Change the base URL and the model id.

curl https://api.geekhub.mx/v1/chat/completions \
  -H "Authorization: Bearer $GEEKHUB_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "anthropic/claude-sonnet-4.5",
    "messages": [{"role": "user", "content": "Hola"}]
  }'
Get an API key

Frequently asked questions

What is Claude Sonnet 4.5?
Claude Sonnet 4.5 is Anthropic’s most advanced Sonnet model to date, optimized for real-world agents and coding workflows. It delivers state-of-the-art performance on coding benchmarks such as SWE-bench Verified, with improvements across system design, code security, and specification adherence. The model is designed for extended autonomous operation, maintaining task continuity across sessions and providing fact-based progress tracking. Sonnet 4.5 also introduces stronger agentic capabilities, including improved tool orchestration, speculative parallel execution, and more efficient context and memory management. With enhanced context tracking and awareness of token usage across tool calls, it is particularly well-suited for multi-context and long-running workflows. Use cases span software engineering, cybersecurity, financial analysis, research agents, and other domains requiring sustained reasoning and tool use. Claude Sonnet 4.5 runs on the Geek Hub API (OpenAI-compatible). Model id: anthropic/claude-sonnet-4.5.
Is Claude Sonnet 4.5 free?
No. Input is $3.2702 per 1M tokens and output is $16.3509 per 1M tokens on Geek Hub (markup included).
What is the context length of Claude Sonnet 4.5?
Claude Sonnet 4.5 has a 1M tokens context window. It supports up to 64,000 completion tokens.
Does Claude Sonnet 4.5 support tool calling and structured outputs?
Claude Sonnet 4.5 accepts tools and tool_choice for function calling. It also supports structured outputs via a JSON schema in response_format.
When was Claude Sonnet 4.5 released?
Claude Sonnet 4.5 was released on 2025-09-29.

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