Claude Opus 5 (Fast) vs GPT-5.6 Terra Pro: side-by-side summary

Claude Opus 5 (Fast) and GPT-5.6 Terra Pro are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.

Claude Opus 5 (Fast), from Anthropic, has a 1,000,000-token context window and is priced at $10/M tokens input, $50/M tokens output on OpenRouter.

GPT-5.6 Terra Pro, from OpenAI, has a 1,050,000-token context window and is priced at $1/M tokens input, $6/M tokens output on OpenRouter.

Context window

• Claude Opus 5 (Fast): 1,000,000 tokens
• GPT-5.6 Terra Pro: 1,050,000 tokens

Price

• Claude Opus 5 (Fast): $10/M tokens input, $50/M tokens output
• GPT-5.6 Terra Pro: $1/M tokens input, $6/M tokens output

Provided by

• Claude Opus 5 (Fast): Anthropic
• GPT-5.6 Terra Pro: OpenAI

• Claude Opus 5 (Fast) model details, providers and pricing
• GPT-5.6 Terra Pro model details, providers and pricing