OpenCode is a fully open-source, terminal-native AI coding agent with 139,000+ GitHub stars that supports 75+ LLM providers without lock-in. Built with TypeScript and Go, it runs as a TUI (Terminal User Interface), a desktop app, or an IDE extension — adapting to wherever developers already work. Its client/server architecture includes two purpose-built agents: a 'build' agent with full filesystem access for active development, and a 'plan' agent that operates read-only for analysis and review. LSP (Language Server Protocol) integration loads the appropriate language server automatically, giving the LLM accurate type information and symbol definitions. A multi-session system lets developers run parallel agents on the same project and share debugging sessions via links. OpenCode stores no user code or context data, making it viable in privacy-sensitive enterprise environments. It authenticates with GitHub Copilot and ChatGPT Plus/Pro accounts, and supports Anthropic Claude, OpenAI, Google Gemini, Groq, AWS Bedrock, Azure OpenAI, and local Ollama models. With 845 contributors, 755 releases, and over 5 million monthly developers, it has become one of the most adopted open-source developer tools in 2026.