signalSimon Willison's Blog2026-09-29
Claude Sonnet 5.5
Anthropic released Claude Sonnet 5.5, which runs 30% faster and costs up to 30% less than Sonnet 5 while beating it on every benchmark. It now powers the free tier on claude.ai, making it more capable than OpenAI's free tier with Luna 5.6. The model nearly matches Opus 5.5 on coding tasks, and Haiku 5.5 is expected in the coming weeks.
- for who
- Developers and AI enthusiasts evaluating language models for coding and general use.
- why now
- Claude Sonnet 5.5 launches today, giving Anthropic a superior free tier over OpenAI's Luna 5.6.
- what changes
- With Sonnet 5.5 on the free tier, users get a top-tier model at no cost, while developers can achieve higher performance at lower cost and faster speed.
- to do
- Try Claude Sonnet 5.5 on claude.ai's free tier or via API to leverage its speed and cost benefits for coding tasks.
key points
- Sonnet 5.5 is 30% faster and 30% cheaper than Sonnet 5
- Beats Sonnet 5 on every benchmark while priced the same
- Now powers free tier on claude.ai, surpassing ChatGPT's Luna 5.6
#ai#generative-ai#llms#anthropic#claude#pelican-riding-a-bicycle#llm-release4 sources · confidence medium
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