The Best Codex Skills, Curated and Cross-Agent Tested

Short answer: the Codex skills worth installing are the ones that sharpen how Codex plans and verifies work, not the ones that just generate more code. Our current top picks are Matt Pocock's Skills (for the grilling and design discipline that stops Codex building the wrong thing) and the Agentic SEO Skill (for evidence-backed SEO and GEO audits). Every pick below is curated, used in real work, and checked for how it behaves across Codex, Claude Code, and OpenCode.

Codex reads the open SKILL.md format, so most good skills run on it. What we add is judgment: which ones actually earn their place, and where a Claude-first skill loses something on Codex.

What makes a Codex skill worth installing

The best Codex skills are reusable instruction playbooks that tell Codex how to plan, execute, and verify a task. The ones that move the needle tend to do one of three things: force alignment before any code is written, bring in real evidence instead of guesses, or encode a repeatable workflow you would otherwise re-explain every session. The ones that do not are thin wrappers that just nudge the model.

The picks

Curated by the role that needs them. Each entry shows what it does, how it behaves on Codex, our take, and a link to the full writeup with the complete compatibility matrix.

Engineering

Matt Pocock's Skills. A composable set of engineering skills for real software work: grilling sessions, domain modeling, codebase design, TDD, and bug diagnosis. On Codex: works. The skills.sh installer targets Codex directly, and the grilling skill in particular is one of the most cited Codex skills going. Our take: this is engineering judgment written down, an axe-sharpener that aligns the work before Codex writes a line. Read the full Matt Pocock's Skills writeup.

Marketing

Agentic SEO Skill. Deterministic, LLM-first SEO and GEO audits with script-backed evidence and prioritized fixes. On Codex: works (it ships a native Codex install format). Our take: the rare SEO skill that gathers proof before it advises, and its deterministic trigger mapping was built for reliability in Codex and other agent IDEs. We use it ourselves every week. Read the full Agentic SEO Skill writeup.

Operations

n8n Skills. Seven skills that teach an agent to build production-ready n8n workflows through the n8n-mcp server. On Codex: works with caveats. The skills are distributed as a Claude Code plugin, so on Codex you copy the SKILL.md folders into the Codex skills directory and configure the n8n-mcp server yourself. Our take: if you automate with n8n, it is close to mandatory; the setup is the only friction. Read the full n8n Skills writeup.

How to use a skill in Codex

1. Get the skill folder (the directory with its SKILL.md).
2. Put it where Codex looks: its skills directory, or a shared .agents/skills folder in your project. Skills need a name and a description in frontmatter, which the picks above all have.
3. Some skills ship an installer. Matt Pocock's set, for example, installs with the skills.sh CLI and lets you choose Codex as a target.
4. If a skill depends on an MCP server (n8n Skills needs n8n-mcp), configure that server in Codex too.

For the full walkthrough across Codex, Claude Code, and OpenCode, see our guide on how to use Claude skills.

Where to go next

Browse the full Skills Marketplace, or compare across agents with our Best OpenCode Skills and Best Claude Code Skills roundups. The strongest skills are the ones that hold up no matter which agent you run.