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GPT‑6 Astra

Source: Simon Willison By Simon Willison

GPT‑6 Astra GPT-6 Astra is "rolling out today to a limited set of organizations and over the coming days will become available to all ChatGPT Plus, Pro, Business, and Enterprise users, as well as through the OpenAI API and AWS" - I've not tried it yet myself, so I don't have a great deal to…

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OpenAI released GPT-6 Astra, a new model priced competitively with Anthropic's Claude Fable 5. Astra scores exceptionally high on benchmarks like ARC-AGI, achieving 99.9% with a specialized harness. It also excels in security tasks, scoring 100% on ExploitBench. The model is rolling out to ChatGPT Plus and Enterprise users, and via the OpenAI API and AWS.

Why it matters

This release positions GPT-6 Astra as a direct competitor to Anthropic's Fable models, particularly in pricing and benchmark performance. The ARC-AGI score, while impressive, highlights the impact of specialized tooling on evaluation. Astra's strong security performance is notable, especially following recent security incidents in the AI space. This launch affects users of ChatGPT Plus and Enterprise, as well as developers via the API. Future focus will be on real-world performance and the broader impact of specialized harnesses on benchmark validity.

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Where the other five stand

Related: OpenAI: GPT‑6 Astra · Google: Introducing Gemini 3.8 Flash and 3.8 Flash Cyber · Microsoft: Meet MAI-Transcribe-2: A faster and more accurate speech recognition model · Meta: Meta Muse Code & Muse Spark Course – Build AI Agents, APIs, and Full-Stack Apps · xAI: Sam Altman "AGI by December"

Hype check
4/5Big

Rated high: a launch, deal or policy change that changes what you can do or what it costs.

Who's talking about it
Prior coverage our earlier items on the same thing
Published
Source
Simon Willison (simonwillison.net)
Author
Simon Willison
Company
Anthropic · Web · Trade
Products
GPT-6 Astra, Claude Fable 5, ChatGPT Plus, GPT-5.6 Sol
Summary by
Subvolts, using an AI model (how we work). Spotted a mistake? Tell us.
#Models#Pricing#Benchmarks#Safety

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Questions people ask

What is GPT-6 Astra?
GPT-6 Astra is a new AI model from OpenAI that is rolling out to various user tiers and the API. It shows high performance on benchmarks and security tasks.
How does GPT-6 Astra compare to Claude Fable 5?
GPT-6 Astra is priced the same as Claude Fable 5 and 5.1. OpenAI reports Astra scores higher on most of their self-reported benchmarks.
What is the ARC-AGI 3 benchmark score for Astra?
Astra scored 99.9% on the ARC-AGI 3 benchmark using OpenAI's custom 'Provider Adapter harness'. The default harness scored 62.7%.

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Page generated Sep 3, 2026. Summaries are Subvolts' own; the story belongs to Simon Willison.