# AI model releases, September 2026

20 AI model releases we verified for September 2026 from 6 vendors, including GPT-6.1 Sol, Claude Sonnet 5.5, Claude Opus 5.5, Gemini 3.8 Flash TTS and more. Dates, status and a vendor source link for each.

Period: 2026-09-01 to 2026-09-30 · Last verified: 2026-10-26 · Canonical: https://theagenticweekly.com/models/releases/2026-09 · All models: https://theagenticweekly.com/models · JSON: https://theagenticweekly.com/models.json

This lists the releases in our dataset for the period, not every model a vendor shipped. Every row links to the vendor page that states the release date. We did not run any of these models (evidence: Reported).

| Date | Model | Vendor | Status | Release date source |
|---|---|---|---|---|
| 2026-09-29 | [GPT-6.1 Sol](https://theagenticweekly.com/models/gpt-6-1-sol) | OpenAI | generally available | https://developers.openai.com/api/docs/changelog |
| 2026-09-28 | [Claude Sonnet 5.5](https://theagenticweekly.com/models/claude-sonnet-5-5) | Anthropic | generally available | https://www.anthropic.com/news |
| 2026-09-22 | [Claude Opus 5.5](https://theagenticweekly.com/models/claude-opus-5-5) | Anthropic | generally available | https://www.anthropic.com/news |
| 2026-09-22 | [Gemini 3.8 Flash TTS](https://theagenticweekly.com/models/gemini-3-8-flash-tts) | Google | generally available | https://ai.google.dev/gemini-api/docs/changelog |
| 2026-09-22 | [Gemini 3.8 Flash-Lite TTS](https://theagenticweekly.com/models/gemini-3-8-flash-lite-tts) | Google | generally available | https://ai.google.dev/gemini-api/docs/changelog |
| 2026-09-22 | [GPT-6 Luna](https://theagenticweekly.com/models/gpt-6-luna) | OpenAI | generally available | https://developers.openai.com/api/docs/changelog |
| 2026-09-22 | [GPT-6 Sol](https://theagenticweekly.com/models/gpt-6-sol) | OpenAI | generally available | https://developers.openai.com/api/docs/changelog |
| 2026-09-21 | [Grok 4.7](https://theagenticweekly.com/models/grok-4-7) | xAI | generally available | https://docs.x.ai/developers/release-notes |
| 2026-09-17 | [Grok Voice Transcribe 2.0](https://theagenticweekly.com/models/grok-voice-transcribe-2-0) | xAI | generally available | https://docs.x.ai/docs/release-notes |
| 2026-09-15 | [Claude Fable 5.1](https://theagenticweekly.com/models/claude-fable-5-1) | Anthropic | generally available | https://www.anthropic.com/news |
| 2026-09-15 | [Gemini 3.8 Live](https://theagenticweekly.com/models/gemini-3-8-live) | Google | generally available | https://ai.google.dev/gemini-api/docs/changelog |
| 2026-09-15 | [Gemini 3.8 Live Extended Thinking](https://theagenticweekly.com/models/gemini-3-8-live-extended-thinking) | Google | generally available | https://ai.google.dev/gemini-api/docs/changelog |
| 2026-09-10 | [DeepSeek-V4.1-Flash](https://theagenticweekly.com/models/deepseek-v4-1-flash) | DeepSeek | generally available | https://api-docs.deepseek.com/updates/ |
| 2026-09-10 | [GPT-Live 1](https://theagenticweekly.com/models/gpt-live-1) | OpenAI | generally available | https://developers.openai.com/api/docs/changelog |
| 2026-09-09 | [North Small Translate](https://theagenticweekly.com/models/north-small-translate) | Cohere | generally available | https://docs.cohere.com/changelog |
| 2026-09-08 | [GPT-Image-2.5 Flare](https://theagenticweekly.com/models/gpt-image-2-5-flare) | OpenAI | generally available | https://developers.openai.com/api/docs/changelog |
| 2026-09-08 | [GPT-Image-2.5 Sunburst](https://theagenticweekly.com/models/gpt-image-2-5-sunburst) | OpenAI | generally available | https://developers.openai.com/api/docs/changelog |
| 2026-09-03 | [GPT-6 Astra](https://theagenticweekly.com/models/gpt-6-astra) | OpenAI | generally available | https://openai.com/index/gpt-6-astra/ |
| 2026-09-02 | [Gemini 3.8 Flash](https://theagenticweekly.com/models/gemini-3-8-flash) | Google | generally available | https://ai.google.dev/gemini-api/docs/changelog |
| 2026-09-01 | [Claude Mythos 5.1](https://theagenticweekly.com/models/claude-mythos-5-1) | Anthropic | limited access | https://platform.claude.com/docs/en/release-notes/overview |

- **GPT-6.1 Sol** (OpenAI, Sep 29, 2026): OpenAI's near-flagship GPT-6.1 model: OpenAI says it performs close to GPT-6 Astra at a fifth of Astra's price.
- **Claude Sonnet 5.5** (Anthropic, Sep 28, 2026): The mid-priced Claude model: Anthropic says it runs 30%+ faster than Sonnet 5 and costs up to 30% less for most work. Date note: Anthropic's newsroom date. At least one third-party site gives Oct 1; we use the vendor's date.
- **Claude Opus 5.5** (Anthropic, Sep 22, 2026): Anthropic's recommended starting model for most workloads, which Anthropic says leads in agentic coding and knowledge work.
- **Gemini 3.8 Flash TTS** (Google, Sep 22, 2026): Google's flagship creative text-to-speech model, generally available since Sep 22, 2026.
- **Gemini 3.8 Flash-Lite TTS** (Google, Sep 22, 2026): Google's fast, cost-efficient text-to-speech model, generally available since Sep 22, 2026 alongside Gemini 3.8 Flash TTS.
- **GPT-6 Luna** (OpenAI, Sep 22, 2026): OpenAI's low-cost GPT-6 model, the model behind ChatGPT Free and Go according to OpenAI. Date note: OpenAI API changelog: GPT-6 Sol and GPT-6 Luna released together.
- **GPT-6 Sol** (OpenAI, Sep 22, 2026): OpenAI's mid-priced GPT-6 reasoning model, released Sep 22, 2026 with GPT-6 Luna and the model behind paid ChatGPT Chat plans, per OpenAI. Date note: OpenAI API changelog: GPT-6 Sol and GPT-6 Luna released together.
- **Grok 4.7** (xAI, Sep 21, 2026): xAI's newest Grok model; its docs call it "the most capable model we've built".
- **Grok Voice Transcribe 2.0** (xAI, Sep 17, 2026): xAI's speech-to-text model, available since Sep 17, 2026 and the default for the Speech to Text API.
- **Claude Fable 5.1** (Anthropic, Sep 15, 2026): Anthropic's top-priced generally available Claude model, announced alongside the access-limited Claude Mythos on Sep 15, 2026. Date note: Date of the Anthropic announcement "Introducing Claude Mythos and Fable 5.1".
- **Gemini 3.8 Live** (Google, Sep 15, 2026): Google's real-time voice model for the Gemini Live API, generally available since Sep 15, 2026, with a separate Extended Thinking variant.
- **Gemini 3.8 Live Extended Thinking** (Google, Sep 15, 2026): Google's high-reasoning audio-to-audio Live API model with background reasoning, generally available since Sep 15, 2026.
- **DeepSeek-V4.1-Flash** (DeepSeek, Sep 10, 2026): DeepSeek's MIT-licensed V4.1 Flash model with a 1M-token context, released Sep 10, 2026 and updated to the 1017 version on Oct 17, 2026. Date note: V4.1-Flash release; the DeepSeek-V4.1-Flash-1017 update followed on 2026-10-17.
- **GPT-Live 1** (OpenAI, Sep 10, 2026): OpenAI's full-duplex voice model that listens and speaks at once; API general availability on Sep 10, 2026 at $0.05 per minute. Date note: API general availability per the OpenAI API changelog. It reached ChatGPT earlier, on Jul 8, 2026, per OpenAI.
- **North Small Translate** (Cohere, Sep 9, 2026): Cohere's open-weights mixture-of-experts machine-translation model for more than 50 languages, released Sep 9, 2026 for non-commercial use under CC BY-NC 4.0.
- **GPT-Image-2.5 Flare** (OpenAI, Sep 8, 2026): OpenAI's fast image generation model for everyday use, released Sep 8, 2026 alongside GPT-Image-2.5 Sunburst.
- **GPT-Image-2.5 Sunburst** (OpenAI, Sep 8, 2026): OpenAI's most capable image generation and editing model, released Sep 8, 2026, and #1 on the LMArena text-to-image snapshot we cite. Date note: OpenAI API changelog: Sunburst and Flare released together.
- **GPT-6 Astra** (OpenAI, Sep 3, 2026): OpenAI's flagship GPT-6 model for complex reasoning and coding, and its most expensive text model per token. Date note: Announced Sep 3, 2026 as a limited rollout to a set of organizations; OpenAI's announcement says "rolling out today to a limited set of organizations".
- **Gemini 3.8 Flash** (Google, Sep 2, 2026): Google's current fast Gemini model ("most intelligent Flash model" per Google's changelog), replacing Gemini 3.7 Flash.
- **Claude Mythos 5.1** (Anthropic, Sep 1, 2026): Anthropic's access-limited Claude Mythos successor for Project Glasswing participants, launched with Claude Fable 5.1 (release-notes date Sep 1, 2026). Date note: Date of the launch entry in the Claude Platform release notes (API availability).

Data licence: CC BY 4.0. Data: Agentic Weekly (https://theagenticweekly.com), CC BY 4.0.