Claude Opus 5 vs GPT-5.5

Anthropic's Claude Opus 5 against OpenAI's GPT-5.5 — price, context and what each is best at. Both are available through one OpenAI-compatible API.

AnyModel — you pay	Claude Opus 5	GPT-5.5
Vendor	Anthropic	OpenAI
Input / 1M	$0.3	$0.15
Output / 1M	$0.3	$0.15
Context	1M	400K
Best for	Hardest coding tasks	Complex coding

Claude Opus 5

The newest experimental Opus, served through Kiro.

Claude Opus 5 is Kiro's newest experimental flagship for sustained coding, multi-file work, multi-agent coordination and precise code review. AnyModel routes it only through Kiro accounts where live inference has been verified.

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GPT-5.5

OpenAI's flagship for coding, agents and research-grade reasoning.

GPT-5.5 is OpenAI's top general-purpose model and the engine behind modern Codex: state-of-the-art coding, computer use and multi-step reasoning with a 400K-token window on this route. The default pick when you want one model that handles everything.

More about GPT-5.5 →

Quick take: pick GPT-5.5 when cost matters most; pick Claude Opus 5 when you need the largest context. With AnyModel you don't have to choose up front — switch the model id any time.

FAQ

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

GPT-5.5 is cheaper on output tokens ($0.15 vs $0.3 per 1M).

Which has a larger context window, Claude Opus 5 or GPT-5.5?

Claude Opus 5 has the larger context window (1M).