Cline

Open-source VS Code AI agent — Plan/Act mode, MCP Marketplace, BYO key, and 1.5M+ installs by April 2026.

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About Cline

Cline is the open-source (MIT) AI coding agent that integrates directly into VS Code, used by 5M+ developers and 1.5M+ installs by April 2026. It creates and edits files, runs terminal commands, browses the web, and interacts with MCP tools. Plan/Act mode lets you separate strategy from execution. The MCP Marketplace adds database access, web tools, and third-party APIs. Cline itself is free; you BYO key (Anthropic, OpenAI, OpenRouter, AWS Bedrock, Google Vertex, Azure) and pay model providers directly. v3.2 automatic model routing brings typical API costs to $8–$12/mo for moderate use.

Key Features

Open source under MIT license
VS Code extension with 1.5M+ installs
Plan/Act mode for separate planning + execution
MCP Marketplace for extensible AI tooling
BYO key: Anthropic, OpenAI, OpenRouter, Bedrock, Vertex, Azure
Automatic model routing (v3.2) cuts API costs
Open Source Teams free through Q1 2026 then $20/mo (10 free seats)
Web browsing and terminal command execution

Use Cases

Run agentic coding inside VS Code for free
Use Plan/Act mode for transparent multi-step work
Extend via MCP Marketplace tools
BYO API key for full provider choice
Run autonomous browsing + terminal tasks
Replace paid AI tools with open source + BYOK

Pros & Cons

Pros

  • Completely free + open source (MIT)
  • Plan/Act mode keeps humans in the loop
  • Massive user base — robust and battle-tested
  • MCP Marketplace adds extensibility

Cons

  • BYO API costs can climb on premium models
  • VS Code only
  • Requires comfort configuring API providers
  • Quality depends on chosen LLM