2026-09-01T00:00:00.000ZAnthropic · NewsFor builders

Introducing Claude Fable 5.1 and Claude Mythos 5.1

Our most advanced models for coding and knowledge work.

Why it matters

Anthropic published a model update. If you use a hosted chat, read the source before you assume your usual model changed.

What you can do

Claude Fable 5.1 is on the cloud board. List cost is $10 in and $50 out per million tokens.

For builders

Try Claude Fable 5.1. Copy the OpenRouter call.

Copy

curl https://openrouter.ai/api/v1/chat/completions \
  -H "Authorization: Bearer $OPENROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"anthropic/claude-fable-5.1","messages":[{"role":"user","content":"Hello"}]}'

Open the source

See Claude Fable 5.1 Plan a job from this

Introducing Claude Fable 5.1 and Claude Mythos 5.1

Updated 10 min ago

Our most advanced models for coding and knowledge work.

Why it matters

Anthropic published a model update. If you use a hosted chat, read the source before you assume your usual model changed.

What you can do

Claude Fable 5.1 is on the cloud board. List cost is $10 in and $50 out per million tokens.

For builders

Try Claude Fable 5.1. Copy the OpenRouter call.

Copy

curl https://openrouter.ai/api/v1/chat/completions \
  -H "Authorization: Bearer $OPENROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"anthropic/claude-fable-5.1","messages":[{"role":"user","content":"Hello"}]}'

Open the source

See Claude Fable 5.1 Plan a job from this

Introducing Claude Fable 5.1 and Claude Mythos 5.1

Why it matters

What you can do

For builders

Copy

Tags

Introducing Claude Fable 5.1 and Claude Mythos 5.1

Why it matters

What you can do

For builders

Copy

Tags