Method: Research-only comparison of official documentation. No hands-on benchmark or performance ranking.
Start with the job
- You want a coding agent with documented sign-in options.
- You need to distinguish an included plan from separately billed model APIs.
Documented differences
| Consideration | Codex | Gemini CLI |
|---|---|---|
| Focus | An AI coding agent for working through software tasks, available through terminal, editor and cloud experiences. | An open-source terminal coding agent. Its current README directs unpaid and Google One users to Antigravity CLI; verify current access before choosing it. |
| Documented capabilities | Coding agent · Terminal workflow · Editor integration · Cloud coding | Code explanation · Coding agent · Web fetch and search tools |
| Free hosted option | Not verified | Not verified |
| Before choosing | The provider documents ChatGPT plan sign-in and a separate API-key route. Check your plan; API billing is separate. | As checked October 16, 2026, the official README directs unpaid and Google One users to Antigravity CLI. It documents paid organizational Code Assist, API-key and Vertex AI routes. Current free access and replacement-product terms are not verified here. |
Our take
Codex documents ChatGPT plan sign-in and a separate API-key option. Gemini CLI’s current README directs unpaid and Google One users to Antigravity CLI, and documents organizational Code Assist, API-key and Vertex AI access. We have not verified a current Gemini CLI free plan or the replacement product’s eligibility. Compare access, permissions and total model costs before trying either tool.
What this comparison does not establish
- Exact plan prices were not verified and are not compared.
- Documented capabilities can change; verify account access and current terms.
- No affiliate relationship influences this comparison.
Sources and evidence
- 1. OpenAI — official source →Observed Oct 16, 2026 · official
Comparison is limited to capabilities documented in this official source.
- 2. Google — official source →Observed Oct 16, 2026 · official
Comparison is limited to capabilities documented in this official source.
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