Agents UI
Both are open-source, terminal-native agents with MCP support. Codex CLI runs OpenAI models; Gemini CLI runs Google's with a generous free tier. The best way to decide is to run them side by side on the same task.
At a glance
| Feature | Codex CLI | Gemini CLI |
|---|---|---|
| Provider | OpenAI | |
| Price | Included in ChatGPT plans / API usage | Free tier + usage-based |
| Open source | Yes | Yes |
| License | Apache-2.0 | Apache-2.0 |
| Interface | CLI | CLI |
| Terminal-native | Yes | Yes |
| MCP support | Yes | Yes |
When to choose Codex CLI
You're in the OpenAI ecosystem or prefer its models for coding.
Codex CLI strengths
- Open source and scriptable
- MCP support
- Terminal-native workflow
When to choose Gemini CLI
You want a free tier and Google's large-context models.
Gemini CLI strengths
- Open source with a generous free tier
- MCP support
- Large context window
How Agents UI compares
If your work centers on AI coding agents, it's worth weighing a third option. Agents UI is an open-source macOS terminal built specifically to run agents like Claude Code, Codex, and Gemini CLI — with multi-agent orchestration, SSH, and a Python SDK in one workspace. Explore the best terminals for multi-agent workflows to see where it fits.
Frequently asked questions
Is Codex CLI better than Gemini CLI?
Both are open-source, terminal-native agents with MCP support. Codex CLI runs OpenAI models; Gemini CLI runs Google's with a generous free tier. The best way to decide is to run them side by side on the same task.
When should I choose Codex CLI?
You're in the OpenAI ecosystem or prefer its models for coding.
When should I choose Gemini CLI?
You want a free tier and Google's large-context models.