Anthropic's flagship reasoning model — best-in-class long-form writing, nuanced code review, and extended agentic workflows. The "thinking" frontier model.
Claude Opus 4.5 is Anthropic's most capable model and the one we reach for when the task needs judgment, not just token completion. It writes the cleanest long-form prose of any model we tested in 2026, catches subtle bugs in code review, and sustains long agentic runs without going off the rails.
Who it's for: Writers, analysts, and senior engineers who care about quality over raw speed. Especially strong for editing, research synthesis, and multi-step agentic coding.
Claude shows its work. For hard problems it allocates thinking budget, reasons step by step, and self-corrects before answering — the most reliable reasoning mode we tested.
Long-form essays, reports, and edits that read like a human wrote them. Beats GPT-5.1 and Gemini 3 on nuance, tone, and structure in blind tests.
In our diff-review benchmark, Opus 4.5 surfaced edge-case bugs, race conditions, and security issues that other models missed. The default reviewer for serious PRs.
Sustains 30+ minute agentic coding sessions with file edits, test runs, and self-verification — ideal for the Claude Code / agentic workflows.
If quality matters more than speed, Claude Opus 4.5 is the model to default to in 2026. It's our pick for writing, analysis, and serious code review. Pair it with a faster model (Haiku 4.5 or GPT-5-mini) for high-volume cheap calls.
Anthropic's full model family — Haiku, Sonnet, and Opus.
OpenAI's fastest flagship — great all-rounder with image gen.
Google's million-token model with deep search integration.
The AI code editor that pairs perfectly with Opus 4.5.