Claude Opus model releases

Claude Opus 5.5 is Anthropic's frontier model released 2026-09-22, succeeding Claude Opus 5. It targets long-running agentic coding and knowledge work, delivering roughly Claude Fable 5.1-level quality on most tasks at about 40% lower running cost than Opus 5 for a typical token-billed workload. Text and image input, text output; 1,000,000-token context window and 128,000 max output tokens (up to 300k output via the Batch API with a beta header). Reliable knowledge cutoff June 2026 (up from May 2026 on Opus 5). API list pricing: $4 / 1M input, $20 / 1M output, $0.20 / 1M cache reads — a 20% cut to input/output token prices and a 60% cut to cached-read price versus Opus 5.

Anthropic's flagship Opus model, released July 24, 2026 — positioned as the go-to model for most knowledge work and automation, approaching the capability of Claude Fable 5 in many categories at roughly half the price. Built for demanding reasoning, autonomous coding, software development, and long-horizon agentic work. Introduces a five-level 'effort' dial exposed to developers on the Claude API and Platform, letting them trade compute and tokens for capability — at lower effort it preserves much of its performance while using fewer tokens and costing less to run. 1M-token context window (available at standard token pricing, not a separate long-context surcharge) with up to 128K output tokens; text, vision, and code. Standard API pricing $5/$25 per Mtok (the same as its predecessor Opus 4.8), plus a Fast mode at $10/$50. Anthropic describes it as its most aligned Opus model and the least susceptible to being tricked into misuse. Becomes the default model for Claude Max subscribers and is available across Anthropic's paid plans; scores 61 on the Artificial Analysis Intelligence Index. Closed weights; architecture, parameter count, and training compute undisclosed.

Anthropic's most capable model, with strengthened agentic and long-running task performance.

Introduced genuinely autonomous multi-file coding and stronger computer use.

Anthropic's August 2025 Opus point release, focused on stronger coding, reasoning, and agentic reliability over Claude Opus 4. Proprietary API model with text, vision, and code capabilities.