Can I use both Claude Fable 5 and GPT-5.5 through one API?

Yes. ApexApi serves both behind one OpenAI-compatible endpoint and a single ak- key. Switch between them by changing the model slug, so you can A/B them on your own prompts without re-integrating.

Which is cheaper, Claude Fable 5 or GPT-5.5?

Live per-token prices for both are in the table above. Pricing changes over time, so the table reflects the current catalog rather than a fixed number.

How do I switch from Claude Fable 5 to GPT-5.5?

Change one string, the model slug, in your request. Same endpoint, same key, same billing. No new account or SDK.

Claude Fable 5 vs GPT-5.5

The short answer

Claude Fable 5 is Anthropic's most capable widely released model, built for the most demanding reasoning and long-horizon agentic work, with adaptive thinking always on. GPT-5.5 is OpenAI's broad multimodal frontier with strong tool orchestration. Reach for Fable 5 when reasoning depth and sustained autonomous runs are the point; reach for GPT-5.5 when you want a versatile generalist for mixed workloads. Both run on one key, so the cleanest decision is a side-by-side test on your prompts.

At a glance

	Claude Fable 5	GPT-5.5
Maker	Anthropic	OpenAI
Type	chat	chat
Context window	1,000,000 tokens	1,050,000 tokens
Vision input	Yes	Yes
Tool calling	Yes	Yes
Input price	$12.00 /1M	$6.00 /1M
Output price	$60.00 /1M	$36.00 /1M

Prices are live from the catalog and include our service fee.

When to choose Claude Fable 5

•You need the deepest reasoning for hard, high-stakes problems.
•Long-horizon agentic work that must not lose the thread.
•You want thinking depth to scale automatically with the task.

Claude Fable 5 API details →

When to choose GPT-5.5

•You want one broad generalist across text, vision, and tools.
•Function calling and automation are central.
•You prefer OpenAI-style prompting and behavior.

GPT-5.5 API details →

Call both through one API and key

ApexApi serves Claude Fable 5 and GPT-5.5 behind a single OpenAI-compatible endpoint. A/B them by changing one string.

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Frequently asked questions

Can I use both Claude Fable 5 and GPT-5.5 through one API?: Yes. ApexApi serves both behind one OpenAI-compatible endpoint and a single ak- key. Switch between them by changing the model slug, so you can A/B them on your own prompts without re-integrating.
Which is cheaper, Claude Fable 5 or GPT-5.5?: Live per-token prices for both are in the table above. Pricing changes over time, so the table reflects the current catalog rather than a fixed number.
How do I switch from Claude Fable 5 to GPT-5.5?: Change one string, the model slug, in your request. Same endpoint, same key, same billing. No new account or SDK.