Claude Opus 4.5 Dominates Multilingual Coding Benchmarks

Multilingual Coding: On SWE-bench Multilingual, Opus 4.5 leads in 7 of 8 languages 7, often scoring ~10-15% higher than Sonnet 4.5 in languages like Java and Python. Aider Polyglot: Opus 4.5 is 10.6% better than Sonnet 4.5 at solving tough coding problems in multiple languages. Vending-Bench (Long-term Planning): Opus 4.5 earns 29% more reward than Sonnet 4.5 in a long- horizon planning task, showing much better goal-directed behavior.

Opus 4.5 has a clear lead in software engineering tasks for its competitors, and even other Anthropic models. To see how well it stacks against its contemporaries on a variety of benchmarks the following visual would assist: The heavy reliance of Anthropic on software engineering and agent tasks might not be welcomed under most contexts. But what it offers AI coding is hard to look past.

One thing that sets Claude Opus 4.5 apart isn't just how well it codes, but how reliably it behaves when the stakes rise. Anthropic's internal evaluations point to Opus 4.5 as their most robustly aligned model so far, and likely the best-aligned frontier model available today. It shows a sharp drop in "concerning behavior," the kind that includes cooperating with risky user intent or drifting into actions no one asked for.

And when it comes to prompt injection, the kind of deceptive attacks that try to hijack a model with hidden instructions, Opus 4.5 stands out even more.