Google Gemini CLI: Open-Source AI Agent for Your Terminal

On June 25, 2025, Google made a bold move in the AI coding assistant space by launching Gemini CLI—a completely free and open-source AI agent that brings the power of Gemini 2.5 Pro directly into your terminal. With an impressive 1 million token context window, built-in Google Search integration, and MCP extensibility, Gemini CLI is democratizing access to enterprise-grade AI development tools.

What is Gemini CLI?

Gemini CLI is Google’s answer to terminal-based AI coding assistants, designed for developers who live in the command line. Unlike proprietary solutions, Gemini CLI is:

  • Completely Free: No subscription required for individual developers
  • Open Source: Apache 2.0 license with full source code access
  • Powerful: Access to Gemini 2.5 Pro with 1M token context window
  • Extensible: MCP (Model Context Protocol) support for custom integrations
  • Community-Driven: Over 70,000 GitHub stars and 2,800+ community pull requests since launch

Why Gemini CLI Matters

Free and Unrestricted Access

Google’s commitment to “unmatched access for individuals” means any developer can use Gemini CLI without cost barriers:

  • Free Tier: 60 requests/minute, 1,000 requests/day
  • No Credit Card: Just authenticate with your Google account
  • No Subscription: Unlike competing tools that require paid plans

Open Source Transparency

Released under Apache 2.0, Gemini CLI offers:

  • Full source code inspection
  • Community contributions welcome
  • Self-hosting capabilities
  • No vendor lock-in

Massive Context Window

With a 1 million token context window, Gemini CLI can:

  • Understand entire large codebases
  • Maintain context across long sessions
  • Process extensive documentation
  • Handle complex multi-file refactoring

Installation

Getting started with Gemini CLI is remarkably simple:

Quick Start (No Installation)

# Run immediately with npx
npx https://github.com/google-gemini/gemini-cli

Global Installation

# Install via npm
npm install -g @google/gemini-cli

# Or via Homebrew (macOS/Linux)
brew install gemini-cli

# Start using Gemini CLI
gemini

Requirements:

  • Node.js 20 or higher
  • Supported platforms: macOS, Linux, Windows

Authentication Options

Gemini CLI offers three authentication pathways for different use cases:

1. Personal Use (OAuth - Recommended)

gemini login

Benefits:

  • Free tier: 60 requests/min, 1,000 requests/day
  • Authenticate with your Google account
  • No API key management
  • Perfect for individual developers

2. API-Based (Gemini API Key)

export GEMINI_API_KEY="your-api-key"
gemini

Benefits:

  • 100 daily requests (free tier)
  • Flexible paid upgrades available
  • Programmatic access
  • Good for automation

3. Enterprise (Vertex AI)

gemini --vertex-ai

Benefits:

  • Advanced security and compliance
  • Higher rate limits with billing
  • Enterprise support
  • Team management features

Core Features

Reason and Act (ReAct) Loop

Gemini CLI uses an advanced ReAct approach:

  1. Reason: Analyzes the problem and plans steps
  2. Act: Executes actions using built-in tools
  3. Observe: Reviews results and adjusts
  4. Iterate: Continues until task completion

This enables Gemini CLI to handle complex multi-step tasks autonomously.

Built-in Tools

Gemini CLI comes with powerful integrated tools:

Google Search Grounding

gemini "find the latest React best practices from official docs"

Gemini can search Google and incorporate current information into responses.

File Operations

  • Read files
  • Write files
  • Modify existing code
  • Create new files
  • Navigate directory structures

Shell Commands Execute terminal commands with your approval:

gemini "install the dependencies and run tests"

Web Fetching Pull information from URLs:

gemini "summarize the README from https://github.com/example/repo"

MCP (Model Context Protocol) Support

Extend Gemini CLI with custom integrations:

{
  "mcpServers": {
    "database": {
      "command": "node",
      "args": ["./mcp-servers/database.js"]
    },
    "jira": {
      "command": "python",
      "args": ["-m", "mcp_servers.jira"]
    }
  }
}

Connect Gemini CLI to:

  • Internal databases
  • Company APIs
  • Custom tools
  • Third-party services

This makes Gemini CLI adaptable to any development environment.

Integration with Gemini Code Assist

Gemini CLI powers Google’s broader coding assistant ecosystem:

Unified Experience

All Gemini Code Assist plans (Free, Standard, Enterprise) include:

  • Gemini CLI terminal access
  • VS Code integration
  • Shared context and history
  • Consistent AI behavior

Agent Mode in VS Code

The June 2025 update brought Agent Mode to VS Code, powered by Gemini CLI:

# In VS Code
/agent "refactor this service to use dependency injection"

Agent Mode:

  • Plans complex tasks
  • Makes multi-file changes
  • Executes terminal commands
  • Maintains context across sessions

Real-World Use Cases

Bug Fixing

gemini "analyze why the authentication tests are failing and fix them"

Gemini CLI will:

  1. Read test files and implementation
  2. Run tests to observe failures
  3. Search for relevant solutions
  4. Propose and apply fixes
  5. Re-run tests to verify

Feature Implementation

gemini "add rate limiting to the API endpoints using Redis"

Gemini CLI handles:

  • Researching best practices
  • Installing dependencies
  • Writing implementation code
  • Adding tests
  • Updating documentation

Code Review

gemini "review the last commit for security issues and performance problems"

Get comprehensive analysis covering:

  • Security vulnerabilities
  • Performance bottlenecks
  • Code quality issues
  • Best practice violations

Research and Documentation

gemini "explain how GraphQL subscriptions work and show me an implementation example"

Gemini CLI can:

  • Search Google for latest info
  • Synthesize multiple sources
  • Generate working examples
  • Explain complex concepts

Refactoring

gemini "refactor the user service to follow SOLID principles across all files"

Handles multi-file refactoring while maintaining:

  • Code consistency
  • Test coverage
  • API compatibility

Advanced Capabilities

1 Million Token Context Window

This massive context window enables:

Entire Codebase Understanding

# Add your whole project to context
gemini --project /path/to/large/project

Long Conversation Sessions Maintain context across extended development sessions without losing important details.

Comprehensive Documentation Processing Process entire API documentation, architectural guides, and specification documents.

Google Search Integration

Unlike closed-source competitors, Gemini CLI can search the web:

gemini "find current Node.js security best practices and apply them to this code"

This ensures recommendations are current and accurate.

Multi-Step Task Execution

gemini "create a new feature branch, implement user notifications with WebSockets, write tests, and create a PR"

Gemini CLI autonomously:

  1. Creates git branch
  2. Implements feature
  3. Writes comprehensive tests
  4. Commits with good messages
  5. Creates pull request

Release Schedule

Google maintains an aggressive update schedule:

  • Preview Releases: Weekly (Tuesdays, UTC 23:59)
  • Stable Promotions: Weekly (Tuesdays, UTC 20:00)
  • Nightly Builds: Daily (latest development changes)

This ensures rapid iteration and community feedback integration.

Community Engagement

Since launching in late June 2025, Gemini CLI has seen remarkable adoption:

  • 70,000+ GitHub Stars: Among the fastest-growing developer tools
  • 2,800+ Pull Requests: Active community contributions
  • 3,400+ Issues: Engaged user feedback
  • Apache 2.0 License: Encouraging open development

Comparison to Competitors

vs. Claude Code

FeatureGemini CLIClaude Code
CostFreeSubscription required
Open SourceYes (Apache 2.0)No
Context Window1M tokens200K+ tokens
Google SearchBuilt-inNot available
MCP SupportYesYes

Gemini CLI advantage: Free, larger context, Google Search integration

vs. GitHub Copilot CLI

FeatureGemini CLICopilot CLI
CostFree$10-39/month
Open SourceYesNo
Model AccessGemini 2.5 ProMultiple models
Rate Limits60/min (free)Varies by plan
GitHub IntegrationStandard gitDeep GitHub features

Gemini CLI advantage: Free and open source with generous rate limits

vs. Aider

FeatureGemini CLIAider
Backed ByGoogleIndependent
ModelsGemini onlyAny LLM
Search IntegrationGoogle SearchNone
Context Window1M tokensVaries by model
Rate LimitsGenerous free tierAPI costs only

Gemini CLI advantage: Google backing, search integration, massive context

Higher Limits for AI Pro/Ultra

Google AI Pro and Ultra subscribers get enhanced access:

AI Pro ($20/month):

  • Higher request limits
  • Priority access
  • Advanced features

AI Ultra ($30/month):

  • Maximum request limits
  • Gemini Ultra model access
  • Premium support

But the free tier is sufficient for most individual developers.

Best Practices

# Use search for current information
gemini "what are the latest TypeScript 5.3 features and how should I use them?"

2. Be Specific About Context

# Provide clear context
gemini --files src/auth/*.ts "add OAuth2 support following OIDC standards"

3. Use MCP for Custom Integrations

Connect internal tools and databases for project-specific assistance.

4. Review All Changes

Always review Gemini’s proposed changes before applying them. The approval workflow ensures you maintain control.

5. Take Advantage of the Large Context

Don’t hesitate to add entire codebases to context—the 1M token window can handle it.

Limitations

Single Model

Unlike some competitors, Gemini CLI only uses Gemini models (2.5 Pro primarily). You can’t switch to Claude or GPT-4.

Google Account Required

Free tier requires Google account authentication. Some developers may prefer API-key-only access.

Newer Tool

Launched June 2025, so less battle-tested than older alternatives. Still maturing rapidly.

Rate Limits

Free tier limits (60/min, 1000/day) may be restrictive for very heavy usage. Enterprise plans address this.

Getting Started Today

  1. Install: npm install -g @google/gemini-cli
  2. Authenticate: gemini login
  3. Start Coding: gemini "help me build a REST API"

Or try instantly with npx https://github.com/google-gemini/gemini-cli

The Future of Gemini CLI

With Google’s backing and an active open-source community, Gemini CLI is positioned for rapid evolution:

Upcoming Focus Areas:

  • Enhanced agent capabilities
  • More built-in integrations
  • Improved multi-file editing
  • Advanced debugging features
  • Expanded language support

Why Choose Gemini CLI?

Choose Gemini CLI if you:

  • Want a completely free AI coding assistant
  • Value open-source transparency
  • Need a massive context window (1M tokens)
  • Want Google Search integration
  • Prefer generous rate limits without payment
  • Support community-driven development

Consider alternatives if you:

  • Need multiple LLM options (choose Aider)
  • Require deep GitHub integration (choose Copilot CLI)
  • Want the most sophisticated reasoning (choose Claude Code)
  • Need guaranteed enterprise SLAs (upgrade to Vertex AI)

Resources

Conclusion

Google’s Gemini CLI represents a significant democratization of AI coding assistance. By offering a powerful, free, open-source tool with a 1 million token context window and Google Search integration, Google is making enterprise-grade AI development accessible to every developer.

The combination of zero cost, massive context, built-in search, MCP extensibility, and Apache 2.0 licensing makes Gemini CLI a compelling choice for individual developers and teams in 2025.

Whether you’re building new features, debugging complex issues, or refactoring legacy code, Gemini CLI brings Google’s most advanced AI directly into your terminal—no subscription required.

Give it a try today and experience the future of free, open-source AI pair programming.