Claude Sonnet 5.5
Anthropic's fast, capable middle model. It scores close to the flagships and writes faster than Opus.
Anthropic, reasoning. Checked 30 October 2026.
Where to use it through an API
Anthropicclaude-sonnet-5-5- Vercel AI Gateway
anthropic/claude-sonnet-5.5
The maker publishes its own benchmarks and limits on its model page.
How it compares
The models just above and below it on the Artificial Analysis Intelligence Index.
| Model | Index | Context | Speed |
|---|---|---|---|
| Claude Opus 5.5 | 58 | 1M | 97/s |
| GPT-6 Astra | 57 | 1M | 76/s |
| GPT-6.1 Sol | 55 | 1M | 79/s |
| Claude Sonnet 5.5 | 54 | 1M | 138/s |
| GPT-6.1 Terra | 51 | 1M | 91/s |
| Claude Fable 5.1 | 50 | 1M | 64/s |
| Gemini 4 Argon | 50 | 1M | 83/s |
Use Claude Sonnet 5.5 with every other AI at once
Put Claude Sonnet 5.5 in one panel and ChatGPT, Claude, Gemini or any of 300+ models in the others. One message goes to all of them, answers arrive side by side, and test mode times them and hides the names so you judge fairly. Pro is free with a follow on X, and you use your own keys.
Questions
Is there a free Claude Sonnet 5.5 API?
Not that we found. Claude Sonnet 5.5 is paid per token through Anthropic and Vercel AI Gateway.
What is the Claude Sonnet 5.5 model id?
Anthropic: claude-sonnet-5-5; Vercel AI Gateway: anthropic/claude-sonnet-5.5.
How does Claude Sonnet 5.5 score?
54 on the Artificial Analysis Intelligence Index at its max setting, checked 30 October 2026.
Can I use Claude Sonnet 5.5 with ChatGPT, Claude and Gemini at the same time?
Yes. MultiScreenAI puts Claude Sonnet 5.5 in one panel and other models in the others, sends one message to all of them and shows the answers side by side.