Claude Opus 5 vs GPT-5.6 Sol

Claude Opus 5 and GPT-5.6 Sol are both available through FastRouter's OpenAI-compatible API, so switching between them is a change of model id, not a new integration.

Claude Opus 5, from Anthropic, has a 1,000,000-token context window, costs from $5.00/1M input and $25.00/1M output tokens across 3 providers and scores 48.1 on the Artificial Analysis Intelligence Index.

GPT-5.6 Sol, from OpenAI, has a 1,050,000-token context window, costs $4.00/1M input and $20.00/1M output tokens and scores 42.3 on the Artificial Analysis Intelligence Index.

GPT-5.6 Sol is the cheapest on input, 1.3× cheaper than the next model, GPT-5.6 Sol has the largest context window, Claude Opus 5 scores highest for intelligence, GPT-5.6 Sol leads on coding and Claude Opus 5 has the highest throughput.