These are the two strongest coding models money can buy in 2026. GPT-5.2-Codex is a version of GPT-5.2 tuned for agentic coding, with context compaction for long-horizon work, stronger large-change performance on refactors and migrations, better Windows support and significantly stronger cybersecurity capabilities. It's built to grind through big, multi-file engineering tasks autonomously.
Claude Opus 4.5 posts class-leading SWE-bench Verified scores and is renowned for clean, well-structured code and reliable long agent runs. In head-to-head use, Codex is the bolder, more aggressive refactorer with security strengths, while Opus produces the cleanest, most consistent diffs. Both are premium-priced, and independent evals show them trading the lead. The right pick depends on whether you value aggressive scale or pristine consistency.
Which should you choose?
GPT-5.2-Codex
GPT-5.2-Codex · 400K context
Pick it if
you need aggressive, large-scale, security-aware engineering.
Claude Opus 4.5
Claude Opus 4.5 · 200K context
Pick it if
you want the cleanest, most consistent code output.
GPT-5.2-Codex wins on large refactors, migrations and security-aware automation; Claude Opus 4.5 wins on code cleanliness and consistency. They're the top two: test both on your codebase.
Questions
Which scores higher on SWE-bench?
Claude Opus 4.5 posts class-leading SWE-bench Verified scores; GPT-5.2-Codex is highly competitive, especially on large structured changes.
Which is better for security work?
GPT-5.2-Codex emphasises significantly stronger cybersecurity capabilities, an explicit focus of its release.