All three cost the same on a subscription — $20/month gets you the terminal agent — and all three can also run on an API key for pay-per-token billing. The choice is about which model ecosystem you want driving your terminal.
| Subscription | Backed by | Power tiers | |
|---|---|---|---|
| Claude Code | Claude Pro $20 | Opus 5 (default since late July 2026) | Max $100 / $200 |
| Codex CLI | ChatGPT Plus $20 | GPT-5.5 family, GPT-5.3-Codex | Pro $200 |
| Gemini CLI / Antigravity | free tier, then $20 | Gemini | Ultra $100 / $200 |
Two things worth knowing. Claude Code ships with every paid Claude plan and now defaults to Opus 5 — and Claude still tends to lead independent coding benchmarks, so if raw code quality in the terminal is the goal, it's the front-runner. Codex CLI comes with ChatGPT Plus and also shows up in an IDE extension and SDK, so a $20 ChatGPT sub covers more surface than just the terminal.
Gemini's situation changed mid-2026: Google ended consumer authentication for the standalone Gemini CLI in June, folding it into "Antigravity" and routing paid access through Gemini Code Assist. There's still a free tier, then $20, then Ultra tiers that scale quota linearly.
If you already pay for one of the three assistants, use its terminal agent first — you're not saving money by adding a second. If you're choosing fresh: Claude Code for code quality and the Opus default, Codex CLI if you want the ChatGPT ecosystem and the IDE extension too, Gemini/Antigravity if you're in [Google Cloud](/entry/eks-vs-gke-vs-aks-managed-kubernetes-pricing-and-the-part-that-isnt-the-control-) and want the free tier to start.