Comparison
Claude Code vs Codex
How the two compare on the things that decide whether your setup carries over: open standards, license, models and where they run.
| Claude Code | Codex | |
|---|---|---|
| Maker | Anthropic | OpenAI |
| License | Proprietary | Apache-2.0 |
| Models | Anthropic Claude models | OpenAI models |
| Runs in | Terminal, IDE, Desktop, Web | Terminal, IDE, Desktop, Web |
| MCP | MCP: supported | MCP: supported |
| Agent Skills | Agent Skills: supported | Agent Skills: supported |
| AGENTS.md | ?AGENTS.md: not yet verified | AGENTS.md: supported |
| ACP | ACP: supported | ACP: supported |
Key differences
- Codex is open source (Apache-2.0); Claude Code is proprietary. If you need to self-host, audit or fork the harness, that settles it.
- Models: Claude Code runs Anthropic Claude models; Codex runs OpenAI models.
- Codex supports AGENTS.md; we have not verified it for Claude Code.
- Both support MCP, Agent Skills, ACP, so MCP servers, skills and repo instructions you set up carry over if you switch.
In their own words
Claude Code
Anthropic's agentic coding tool. Reads the codebase, edits files, runs commands, and extends through MCP servers, Skills, subagents, hooks and plugin marketplaces. Project instructions live in CLAUDE.md.
FAQ
- Is Claude Code or Codex open source?
- Claude Code is proprietary. Codex is open source under Apache-2.0.
- Do Claude Code and Codex support MCP servers?
- Claude Code: yes. Codex: yes.
- Can I reuse Agent Skills between Claude Code and Codex?
- Yes. Both read the open Agent Skills (SKILL.md) format, so the same skill folder works in both.
Set up MCP servers in either one
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Reviewed Oct 5, 2026.