Is Codex or Kiro open source?

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

Can I reuse Agent Skills between Codex and Kiro?

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); Kiro is proprietary. If you need to self-host, audit or fork the harness, that settles it.
Codex also runs in Terminal, Desktop, Web; Kiro also runs in CLI.
Codex supports AGENTS.md; we have not verified it for Kiro.
Both support MCP, Agent Skills, ACP, 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.

Kiro

Spec-driven agentic IDE and CLI: turns prompts into requirements, designs and tasks before writing code.

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

Reviewed Oct 5, 2026.