Gemini CLI Review 2026: Google's Open-Source Terminal Agent

What Is Gemini CLI?

Gemini CLI is Google’s open-source AI agent that runs in the terminal, released under the Apache 2.0 license. It uses a ReAct (Reason and Act) loop with built-in tools for file operations, shell commands, web fetching, and Google Search grounding. It can be used free with a Google login or with a Google AI subscription for higher limits, and also supports API key access.

What Sets It Apart

Gemini CLI’s generous free tier is its most immediate differentiator. With a Google login, you get enough daily usage for a full day of active development using both Gemini Flash and Pro models. For students, hobbyists, or developers evaluating terminal-based AI agents, the cost barrier is effectively zero — meaningfully more generous than most competitors.

The open-source Apache 2.0 license provides real transparency. You can inspect every tool call, audit what data leaves your machine, and fork the project for custom needs. The 1M token context window is among the largest available in CLI agents, letting you hold substantial portions of a codebase in memory during a session. MCP server support makes it extensible — you can connect it to databases, internal APIs, and custom tooling without waiting for Google to add integrations.

The main trade-off is that Gemini CLI is locked to Google’s Gemini model family. If Gemini produces weaker results for your specific language or codebase, you cannot swap in a different model. On paid Google AI plans, the quota is also shared with Gemini Code Assist, which can create unexpected limits for heavy users of both tools.

Who It’s For

• Developers who want a capable, free terminal AI agent with no API costs
• Open-source advocates who want to inspect and modify their tools
• Terminal-first developers working in Vim, Neovim, or tmux
• Teams already invested in the Google ecosystem
• Developers who want model flexibility should consider Aider or Claude Code instead

Sources

• Gemini CLI on GitHub
• Google AI Developer Tools
• Google AI Pricing