ASTRA FIRST · CHOOSE BY THE JOB

Astra is available. Here is the primary route and when another model fits better.

Three task-specific options, compared honestly.

RELEASED · ACCESS EXPANDING

Use GPT-6 Astra through the route that fits.

Astra is available through multiple documented routes. ChatGPT, Work, Codex, API, Copilot, Foundry, and third-party catalog access each have their own plan, account, client, or provider rules.

A route listing is not a promise that your account, plan, workspace, or region is eligible.

Check your Astra route See how to start

Official routes lead. Third-party routes are labeled separately.

The provider relationships below are shown beside each action. Affiliate links are marked sponsored. HowToUseAstra may earn a commission if you purchase through this link. Affiliate relationships do not change our editorial ranking.

Krater is an independent third-party catalog. Its listing is evidence of what Krater says it offers, not OpenAI endorsement or proof that its route has the same API, limits, price, or account access as OpenAI direct.

Astra is real and available through multiple routes. Start with the primary access gateway, then choose another model only when workflow, model family, deliberation, or economics point elsewhere. Each remains distinct from GPT-6 Astra.

WHEN ANOTHER MODEL FITS BETTER

Choose by the job, not by the release headline.

Astra is the primary route. Use another model only when its workflow, access, or economics are a better fit.

Stay in OpenAI's ecosystem

GPT-5.6 Sol

The most direct stepping stone if your target is OpenAI’s tooling, model naming, and developer workflow.

Why it fits: Krater’s current catalog lists GPT-5.6 Sol and its model page describes complex reasoning, coding, and agentic workflows.
Honest limit: It is GPT-5.6 Sol, not GPT-6 Astra. Similar lineage does not establish Astra-level capability, access, or pricing.

GPT-5.6 Sol on Krater Model page

Hardest single-model work

Claude Fable 5.1

A strong candidate when the job is difficult coding, research, knowledge work, or a long-running agent task.

Why it fits: Anthropic describes Fable 5.1 as its most capable generally available model for demanding reasoning and long-horizon agentic work, and Krater lists it in the current catalog.
Honest limit: It is Anthropic’s model, not GPT-6 Astra. Safeguards, plan limits, retention, and actual task performance still need to be checked for your use case.

Claude Fable 5.1 on Krater Model page

Several models checking

Fusion

A different answer to uncertainty: ask several models to analyze in parallel, then use synthesis instead of relying on one model.

Why it fits: Krater’s model page describes Fusion as a small multi-model deliberation that analyzes a prompt in parallel with web search and fetch enabled.
Honest limit: Fusion is a Krater product, not itself a frontier model and not GPT-6 Astra. The page does not prove that it is OpenRouter Fusion.

Fusion on Krater Model page

These are alternatives, not Astra. Their product terms and capabilities remain separate.

HowToUseAstra may earn a commission if you purchase through this link. It does not affect our recommendations.

PRODUCT SOURCES

Product claims stay beside the action so the comparison remains inspectable.

The honest summary

Now that GPT-6 Astra is available through multiple documented routes, compare it against the current frontier when another workflow is a better fit. One model can reason carefully for a long time; several models can check each other. Check the availability tracker before choosing.

Questions people ask

Can I use OpenAI Astra today?

OpenAI released GPT-6 Astra on September 3, 2026, and the current site state recognizes multiple documented routes. Check the official product or provider surface for your account and region.

What can I use for difficult work besides Astra?

The direct Astra route is primary, but alternatives can be better when the job, access, workflow, or economics point elsewhere: GPT-5.6 Sol for an OpenAI-family migration path, Claude Fable 5.1 for difficult single-model work, or Krater’s Fusion for multi-model deliberation. None is GPT-6 Astra, and Fusion is not itself a frontier model.

Will paying for ChatGPT get me Astra earlier?

OpenAI’s current ChatGPT guidance says GPT-6 Pro, powered by Astra, is rolling out for Pro $100, Pro $200, Business, and Enterprise. Plus plans include Astra in ChatGPT Work and Codex as it rolls out; availability can differ between Chat, Work, and Codex. Account and region eligibility still need to be checked in OpenAI’s current product surfaces.

Is any public model able to solve open math problems like Astra did?

No public model has a comparable published record of solving long-standing open problems. That capability is, so far, the entire distinction of the Astra announcement.

ASTRA UPDATES

Keep the useful Astra updates coming

We’ll send occasional source-backed updates as access, pricing, and real-world tests change. This is an independent list, not an OpenAI waitlist.