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Serena

LSP-powered semantic coding agent via MCP

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Serena is a free, open-source coding agent toolkit that provides IDE-like semantic code retrieval and editing capabilities to any LLM via the Model Context Protocol (MCP). Built on Language Server Protocol (LSP) integration, it enables symbol-level navigation, cross-file refactoring, and relational code understanding across Python, TypeScript, Go, Rust, Java, PHP, and more — without requiring file-level reads or text-based search.

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Serena bridges the gap between AI coding agents and real IDE intelligence. While most coding agents rely on grep-like text search and string replacements, Serena leverages Language Server Protocol (LSP) integration to provide genuine semantic understanding — tools like find_symbol, find_referencing_symbols, and insert_after_symbol that operate at the code entity level. This means your LLM can navigate complex codebases the way an experienced developer uses their IDE, understanding relationships between functions, classes, and variables across entire projects.

The toolkit integrates with coding workflows in multiple ways: as an MCP server for Claude Code, Claude Desktop, Cursor, and other MCP-compatible clients; through Agno for model-agnostic agent creation with any LLM provider; or by incorporating its tools directly into frameworks like Pydantic AI or LangGraph. Serena supports 40+ programming languages out of the box with direct support for Python, TypeScript, JavaScript, PHP, Go, Rust, C/C++, and Java, plus community-tested support for Ruby, C#, Kotlin, and Dart.

Built by Oraios AI as a free alternative to subscription-heavy coding tools, Serena runs entirely locally and keeps your codebase private. It offers configurable modes for different workflows — planning mode, interactive mode, one-shot execution — and customizable contexts through YAML configuration. The project has earned strong community adoption with developers frequently describing it as a game changer for agent-assisted coding, particularly for large codebases where file-based approaches break down.

Pricing

Default LSP backend is free/open-source; optional JetBrains plugin is paid/free-trial; model costs external

Platforms

MCP Server, Claude Code, Cursor, JetBrains, VS Code, CLI

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