Is Codex or Amp open source?

Codex is open source under Apache-2.0. Amp is proprietary.

Can I reuse Agent Skills between Codex and Amp?

Yes. Both read the open Agent Skills (SKILL.md) format, so the same skill folder works in both.

Comparison

How the two compare on the things that decide whether your setup carries over: open standards, license, models and where they run.

Codex is open source (Apache-2.0); Amp is proprietary. If you need to self-host, audit or fork the harness, that settles it.
Codex also runs in Desktop, Web.
Codex supports ACP; we have not verified it for Amp.
Both support MCP, Agent Skills, AGENTS.md, so MCP servers, skills and repo instructions you set up carry over if you switch.

Codex

OpenAI's coding agent across CLI, IDE, ChatGPT and cloud. One of the originators of AGENTS.md, with Skills, MCP and a plugin marketplace.

Amp

Frontier coding agent for terminal and editor. Co-created the AGENTS.md convention and supports Agent Skills.

Is Codex or Amp open source?: Codex is open source under Apache-2.0. Amp is proprietary.
Do Codex and Amp support MCP servers?: Codex: yes. Amp: yes.
Can I reuse Agent Skills between Codex and Amp?: Yes. Both read the open Agent Skills (SKILL.md) format, so the same skill folder works in both.

Reviewed Oct 5, 2026.