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

> Claude 5.5, GPT-6.1 Terra, Gemini 4 Argon and a wave of open-weight models, each with the date its maker gives.

URL: https://claudegpt.si/news/new-ai-models-autumn-2026-roundup  
Published: 2026-10-27T05:28:03.768Z  
Updated: 2026-10-28T05:28:04.281Z  
Author: ClaudeGPT Si Newsroom  
Section: AI Models  
Topics: AI models, Language models, Open-weight models  
Publisher: ClaudeGPT Si

## Key takeaways

- Anthropic released Claude Fable 5.1, Opus 5.5, Sonnet 5.5 and Haiku 5.5 between September 1 and October 7, 2026.
- OpenAI's newest model is GPT-6.1 Terra, released October 26, after GPT-6 Astra, Sol, Luna and GPT-6.1 Sol in September.
- Google announced Gemini 4 Argon on October 13, and open-weight releases included Kimi K3.1 Pro, Flint, Nanbeige4.3-33B and Unlimited OCR 2.

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](https://claudegpt.si/category/models), 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](https://claudegpt.si/news/claude-news-5-5-family-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:

| Date | Model | What OpenAI says it is for |
| --- | --- | --- |
| September 3 | GPT-6 Astra | Its most capable model, for the hardest end-to-end work |
| September 22 | GPT-6 Sol and GPT-6 Luna | Reasoning models with text and image input |
| September 29 | GPT-6.1 Sol | Complex coding and professional work |
| October 26 | GPT-6.1 Terra | Visual reasoning, computer use and clear writing |

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](https://claudegpt.si/news/openai-gpt-6-1-terra) 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](https://claudegpt.si/news/gemini-4-argon-how-to-use) 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](https://claudegpt.si/feed.xml) 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.

## Frequently asked questions

### What is the newest AI model?

As of October 28, 2026, the newest major release here is OpenAI's GPT-6.1 Terra from October 26, followed a day later by Baidu's Unlimited OCR 2 and Google's Genie 4 research preview.

### Which new AI models can I download?

Flint, Nanbeige4.3-33B and Unlimited OCR 2 have weights on Hugging Face. Moonshot says Kimi K3.1 Pro weights will be released by November 4.

## Sources

- [Models overview](https://platform.claude.com/docs/en/models/overview), Anthropic
- [Claude Platform release notes](https://platform.claude.com/docs/en/release-notes/overview), Anthropic
- [API changelog](https://developers.openai.com/api/docs/changelog), OpenAI
- [GPT-6.1 Terra model page](https://developers.openai.com/api/docs/models/gpt-6.1-terra), OpenAI
- [Gemini 4 Argon: Built to solve your hardest problems](https://blog.google/innovation-and-ai/models-and-research/gemini-models/introducing-gemini-4-argon/), Google
- [Genie 4: A new generation of world simulation](https://deepmind.google/blog/genie-4-a-new-generation-of-world-simulation/), Google DeepMind
- [Introducing Kimi K3.1 Pro](https://www.kimi.ai/blog/kimi-k3-1-pro), Moonshot AI
- [Flint model card](https://huggingface.co/RecursiveSI/flint), Recursive
- [Nanbeige4.3-33B model card](https://huggingface.co/Nanbeige/Nanbeige4.3-33B), Nanbeige
- [Unlimited OCR 2 model card](https://huggingface.co/baidu/Unlimited-OCR-2), Baidu
- [Dessa](https://block.xyz/dessa), Block