Anthropic’s Claude Opus 5.5 scored 1,818 points at its Max setting to lead Code Arena’s WebDev leaderboard, while OpenAI’s GPT-6 Sol at Max placed fourth with 1,689 points.

Opus 5.5 also led the Artificial Analysis Coding Agent Index, scoring 66 at maximum effort in Claude Code, compared with 60 for Opus 5 and 62 for Claude Fable 5.1. That improvement came at a higher cost: it used $13.04 per task, up 21% from Opus 5’s $10.79, as greater token use outweighed lower token prices.

Released Sept. 22, Opus 5.5 costs $4 per million input tokens and $20 per million output tokens, both down 20% from Opus 5. Anthropic’s tests at default settings showed a 40% reduction in cost on typical workloads, distinct from the maximum effort settings used in the coding evaluation. The model also generates output more than 30% faster than Opus 5.