Claude Sonnet 4.5 vs GPT-5.5

Compare Claude Sonnet 4.5 and GPT-5.5 side by side. See pricing, capabilities, context length, and performance. Use both on Krater.ai from $20/mo.

Claude Sonnet 4.5 vs GPT-5.5: strengths, best use cases and how to run both side by side. The live page adds context windows, token pricing and more comparisons once it loads.

Try both on Krater

Run Claude Sonnet 4.5 and GPT-5.5 on the same prompt in the Krater Model Arena, then keep the winner in your workflow. One subscription covers both, from $20 a month.

Open Krater chat · Claude Sonnet 4.5 on Krater · GPT-5.5 on Krater

What each model is best at

Claude Sonnet 4.5

A major update to the Claude Sonnet line, offering near-Opus-level reasoning with significantly faster response times. Claude Sonnet 4.5 is the sweet spot of capability and speed.

Strengths

  • Near-Opus reasoning at Sonnet speed
  • Excellent coding and debugging
  • Strong creative writing abilities
  • Fast for its capability level

Best for

  • Professional development workflows
  • Complex analysis that needs speed
  • Content creation and editing
  • Balanced performance applications

GPT-5.5

OpenAI's GPT-5.5 is the next-generation flagship model with a 1M-token context window, sharper reasoning, and improved instruction following over GPT-5.3. Available now on Krater alongside 500+ other AI models.

Strengths

  • Frontier reasoning across math, code, and analysis
  • 1M-token context for long documents and codebases
  • Improved instruction following and steerability
  • Strong multimodal understanding (text + vision)

Best for

  • Complex multi-step reasoning tasks
  • Long-document analysis and summarization
  • Production-grade coding assistance
  • Agentic workflows with tool use

How we compare models

Our tested head-to-heads run the same prompt set through both models in the Model Arena, then rank answers blind. Read the testing methodology, or browse every comparison.