OpenAI put GPT-6 in front of every ChatGPT user on the same day Anthropic slashed small-model prices to match.

The AI price war has reached the cheapest tier.

OpenAI began rolling out GPT-6 on 7 Oct. Paid plans get GPT-6 Sol, and Free and Go users get the lighter GPT-6 Luna from 8 Oct, with a new "Intelligent UI" that adds charts, forms and buttons to answers.

The same day, Anthropic released Claude Haiku 5.5 at $0.10 per million input tokens and $0.50 per million output for prompts under 100K tokens.

That is a 90% cut on Haiku 4.5's $1/$5 for short prompts and 50% for longer ones, which Anthropic says works out to ~75% cheaper on average. 

Anthropic also halved Sonnet 5.5 cache-read prices to $0.10 per million tokens. VentureBeat notes that the new rates match GPT-6 Luna's.