Always GPT-4o
Fouro uses one server-selected model. If GPT-4o is unavailable, Fouro tells you instead of substituting another model.
GPT-4o, still here.
Your familiar 4o.
Fouro is a focused place to talk, vent, reflect, or think something through with GPT-4o. No model menu. No silent switching. Just start talking.
No account or card required to start.
Why now
GPT-4o left ChatGPT. It did not disappear.
OpenAI retired GPT-4o from ChatGPT in February 2026 while keeping the model available through its API. Fouro uses that API model through OpenRouter and wraps it in a calm, personal chat experience built for continuity.
Read OpenAI's retirement announcementThe Fouro difference
Less product. More conversation.
Start before signing up
Try five guest chats per day. Guest conversations disappear when you leave and never become saved Memory.
Continuity on your terms
Sign in for durable history and Memory you can review, edit, or delete. Only a compact recent subset is used in each chat.
Simple pricing
Start free. Stay because it feels right.
Free
$0
- 10 signed-in chats per day
- 100 signed-in chats per month
- Saved history and Memory
Fouro Pro
$25 / month
- No product chat-count limits
- Full conversation history
- Personal Memory across chats
Reasonable provider, token, storage, concurrency, and service safety ceilings still apply.
Good to know
Fouro is its own product.
Is Fouro the old ChatGPT experience?
No. Fouro uses OpenAI's GPT-4o API model, but it does not reproduce ChatGPT's private prompts, routing, tools, or interface.
Is Fouro affiliated with OpenAI?
No. Fouro is an independent service and is not affiliated with or endorsed by OpenAI.
Is this therapy?
No. Fouro can support conversation and reflection, but it is not a therapist, emergency service, or substitute for professional advice.
GPT-4o, still here.