Claude Opus 5.5 High

Claude Opus 5.5 High holds the second position on the LMSYS Arena text leaderboard with an Elo score of 1507 across 6,272 blind human evaluations. Developed by Anthropic and released in October 2026, this frontier model achieves the industry's highest BenchAlign composite score of 86.39, with a strict 90 percent confidence interval between 80.5 and 92.3. Configured with a 1-million-token context window and priced at $8.00 per 1M input tokens, Opus 5.5 delivers state-of-the-art results in rigorous codebase synthesis, multi-hop logical deductions, and enterprise workflow execution.