New AI models: what Anthropic, OpenAI, Google and open labs released

The new AI models of autumn 2026 come from four directions at once: Anthropic finished its Claude 5.5 family, OpenAI built out its GPT-6 line, Google announced Gemini 4 Argon, and open-weight labs shipped models you can download. This roundup lists each release with the date its maker gives, as of October 28, 2026, and links to our full coverage.

We track every launch in the AI Models section of ClaudeGPT Si, with sources on each story. Here is the season so far.

Anthropic: the Claude 5.5 family

Anthropic's release notes date four model launches since September:

• Claude Fable 5.1, September 1, for demanding reasoning and long-horizon agentic work.
• Claude Opus 5.5, September 22, for long-running agentic coding and knowledge work.
• Claude Sonnet 5.5, September 28, the balance of speed and intelligence.
• Claude Haiku 5.5, October 7, for high-volume tasks where latency matters.

Anthropic's models overview tells most developers to start with Opus 5.5 and move to Fable 5.1 only when that falls short. Our Claude 5.5 recap covers the three weeks in which the family arrived.

OpenAI: the GPT-6 line

OpenAI's API changelog shows a release every few weeks:

Terra is the newest. OpenAI's model page lists a context window of 1,050,000 tokens and a June 1, 2026 knowledge cutoff. Our GPT-6.1 Terra report explains where it fits in the line.

Google: Gemini 4 Argon and Genie 4

Google announced Gemini 4 Argon on October 13 and calls it its latest frontier model. Subscribers to Google AI Pro or Ultra get it in the Gemini app and AI Mode in Search, and developers reach it through the paid tier of the Gemini API. Our guide to using Gemini 4 Argon walks through each place it appears.

On October 27 Google DeepMind added Genie 4, a world model that generates interactive scenes with sound. For now it is a research preview for trusted testers.

Open-weight releases

Some of the most interesting new AI models this month are ones you can run yourself:

• Kimi K3.1 Pro from Moonshot AI, released October 23 on the Kimi API and apps. Moonshot says the full weights will follow by November 4.
• Flint from Recursive, October 23, a coding model under Apache 2.0 that activates about 2.5B of its roughly 40B parameters per token.
• Nanbeige4.3-33B, posted to Hugging Face on October 24 under Apache-2.0, aimed at agentic coding.
• Unlimited OCR 2 from Baidu, October 27, an MIT-licensed model that reads long documents in one pass.

Voice: Block's Dessa

Block unveiled Dessa on October 23, a speech-to-speech model trained only on recordings of human conversation. Block says it runs on a MacBook Pro with an M4 Max chip or newer. Access is through a waitlist.

How to keep up

Model pages, changelogs and launch posts are the primary sources, and they are spread across a dozen sites. ClaudeGPT Si reads them, dates every fact and lists its sources under each article. You can follow the models section or add our RSS feed to a reader. If you only care about one lab, its own changelog is still the fastest place to see a release the minute it lands.