Compare

Claude Fable 5.1 vs O3

Pricing per million tokens, context window, capabilities — pulled from each provider's public docs. All 2 are available via the same AIgateway OpenAI-compatible endpoint; flip the model string to switch.

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Claude Fable 5.1
anthropic/claude-fable-5.1
O3
openai/o3
Provider
Anthropic
OpenAI
Family
o-series
Modality
text
text
Context window
1,000,000 tok
200,000 tok
Max output
128,000 tok
100,000 tok
Released
2026-09-01
2026-05-22
License
Proprietary
Open-weight
Input price
$10.00 /1M
$2.00 /1M
Output price
$50.00 /1M
$8.00 /1M
Tools
yes
—
Streaming
yes
yes
Vision
yes
—
JSON mode
yes
—
Reasoning
—
—
Prompt caching
—
—
Batch API
—
—
Try it
Open in playground →
Open in playground →
Claude Fable 5.1
anthropic/claude-fable-5.1
Full spec →

Claude Fable 5.1 is Anthropic's next model in the Fable family, with improvements in agentic coding, long-running agentic workflows, knowledge work, front-end and visual code generation, and finance and analysis tasks. It supports adaptive thinking and a 1M token context window.

Strengths
  • General-purpose chat
  • Long context
  • Tool use
Use cases
ChatbotsContent generationAgentic workflows
O3
openai/o3
Full spec →

o3 is OpenAI’s general-purpose reasoning model, balancing strong analytical performance with reasonable latency and cost.

Strengths
  • General-purpose chat
  • Long context
  • Tool use
Use cases
ChatbotsContent generationAgentic workflows
SWITCH BETWEEN THEM

One key, all 2, one line different.

from openai import OpenAI

client = OpenAI(
    base_url="https://api.aigateway.sh/v1",
    api_key="sk-aig-...",
)

# Claude Fable 5.1
client.chat.completions.create(
    model="anthropic/claude-fable-5.1",
    messages=[{"role":"user","content":"hello"}],
)

# O3
client.chat.completions.create(
    model="openai/o3",
    messages=[{"role":"user","content":"hello"}],
)
Get an AIgateway keyRun an eval on these →