The Best Codex Skills, Curated and Cross-Agent Tested

The single best Codex skill for most product teams right now is the Agentic SEO Skill, because it backs every audit finding with script-collected evidence instead of model guesswork, and it runs cleanly under Codex. Below it, the n8n Skills bundle is the pick if your team automates with n8n. Both selections are hand-checked for how they behave on Codex, not just whether they install.

Codex reads skills from .agents/skills and needs name and description frontmatter, so most well-formed SKILL.md skills port to it. The catch is what degrades: Claude-specific features like hooks and some MCP setups can silently no-op. That is exactly the detail a scraped mega-list will not tell you, and it is the column we fill in for every entry.

How we pick

Every skill here is judged on three things, in this order:

1. Does it solve a real problem a SaaS or product team actually has, not a toy demo.
2. Does it run on Codex, and if something degrades versus Claude Code, we say what and why.
3. Is the source maintained and the install honest.

We curate for quality over coverage. This is a shortlist, not a directory dump. Compatibility flags are AI-inferred today and carry a not-yet-verified note until we run them by hand. That honesty is the whole point.