Claude Opus 5 Fast

• ⚡ Speed-optimized Opus 5, running about 2.5x default speed
• 📏 Full 1M-token context window, same as standard Opus 5
• 🧠 Reasoning, vision, coding, function-calling and web search onboard
• 🏢 Built for agentic coding and professional knowledge work
• 🎯 Effort setting trades intelligence for faster, cheaper output
• 🔧 Same weights as Opus 5, priority serving path, higher token cost
• 🆕 Succeeds Claude Opus 4.8 Fast in the Opus fast family
• 📅 Released alongside Claude Opus 5 in July 2026

Anthropic

Anthropic PBC is an American artificial intelligence company headquartered in San Francisco. Structured as a public benefit corporation, the lab develops large language models under the Claude name, with a research emphasis on building reliable, steerable,…

Claude Opus 5 Fast is the latency-optimized configuration of Anthropic's Claude Opus 5, the flagship of the Opus tier released in July 2026. Rather than a distinct model, fast mode routes requests through a higher-priority serving path so the same Opus 5 weights respond at roughly 2.5 times the default speed, at a higher per-token cost. It keeps the full 1M-token context window and the model's capabilities across reasoning, vision, agentic coding, function calling and web search.

Within its own family, it directly follows Claude Opus 4.8 Fast, inheriting the underlying generational jump from Claude Opus 4.8 to Opus 5. Anthropic says Opus 5 delivers improved performance at the same price as Opus 4.8, and reports it scores 10.2 percentage points higher than Opus 4.8 on the company's internal chemistry benchmark, calling it their most capable generally available model for scientific research.

Opus 5 sits below the Mythos-class Claude Fable 5 in Anthropic's lineup, with Claude Sonnet 5 serving as the more balanced mid-tier option. The fast variant is aimed at interactive work like rapid iteration and live debugging, where lower latency matters more than conserving cost.