Claude news: the Claude 5.5 releases and where to follow the next one

The biggest Claude news of autumn 2026 is the Claude 5.5 family: Anthropic released Opus 5.5, Sonnet 5.5 and Haiku 5.5 between September 22 and October 7, after Claude Fable 5.1 on September 1. To keep up with Claude news as it happens, follow the Models section of ClaudeGPT Si, a free, independent publication that reports each release from Anthropic's own pages and lists its sources under every story.

The Claude releases, in order

All dates come from Anthropic's platform release notes and its announcement pages, read in late October 2026.

Anthropic called Opus 5.5 the first model in the new 5.5 family and said it performs at the level of Fable 5.1 on most work. External evaluators, METR among them, tested it before release. Sonnet 5.5 followed six days later as what Anthropic describes as a clear upgrade over Sonnet 5, and Haiku 5.5 closed the set as its fastest model so far.

The models overview now recommends Opus 5.5 as the starting point for most workloads, with Fable 5.1 kept for the hardest reasoning jobs. Every current model takes text and images, uses tools, and has a 1M token context window. For a closer look at one of them, our report on what Claude Sonnet 5.5 costs sets it beside Opus 5.5.

Other Claude news from October

Model launches were not the only story. A few more items from Anthropic's own pages:

• Agent Skills. On October 22, Anthropic said it is donating Agent Skills, its open standard for giving agents workflows and knowledge, to the Agentic AI Foundation.
• API version 2026-10-21. New major versions of the client SDKs shipped on October 21, now under the Apache 2.0 license.
• Older models. Claude Sonnet 4.5 is scheduled to retire from the API on November 30, 2026, and Anthropic points developers to Sonnet 5.5.
• Company news. Anthropic filed an S-1 with the SEC on October 26, and on October 27 it said it had acquired Mithril Medicine, a small company working on rare forms of muscular dystrophy.

Where to follow Claude news

Anthropic posts announcements on its newsroom and technical changes in its release notes. Those are the primary sources, and they are worth reading in full when a launch matters to your work. The catch is that they cover one company, and they do not explain what a release means next to the rest of the market.

That is the gap ClaudeGPT Si fills. Its Claude tag page gathers every story about Claude in one list, from model launches to practical guides such as how to turn on Claude Code auto mode. Articles show when they were published and last updated, and the site says it is not affiliated with Anthropic and takes no payment for coverage. You can also add the RSS feed to a reader.

When to go straight to Anthropic instead: if you run Claude in production, read the release notes and model deprecation pages directly, because a migration date matters more than any summary.