r33drichards/mcp-js

Overview

An MCP server that exposes a V8 JavaScript runtime as a tool for AI agents such as Claude and Cursor. It supports persistent heap snapshots via S3 or the local filesystem, enabling state to survive restarts. The server is written in Rust and designed for integration with modern AI development environments.

Best for

Best for
Developers building AI agents that need to execute and persist JavaScript state

Use cases

• Executing JavaScript code from AI agents during conversations
• Persisting runtime state across sessions using heap snapshots
• Integrating JavaScript execution into Claude or Cursor workflows

How to use

Install

curl -fsSL https://raw.githubusercontent.com/r33drichards/mcp-js/main/install.sh | sudo bash

Tools exposed

• run_js
• get_execution
• get_execution_output
• cancel_execution
• list_executions
• list_sessions
• list_session_snapshots
• get_heap_tags
• set_heap_tags
• delete_heap_tags
• query_heaps_by_tags

Tested with

Claude Code, Claude Desktop, Cursor

Example client config

{\n  "mcpServers": {\n    "js": {\n      "command": "mcp-v8",\n      "args": ["--stateless"]\n    }\n  }\n}

Notes

An MCP server that exposes a V8 JavaScript runtime as a tool for AI agents such as Claude and Cursor. It supports persistent heap snapshots via S3 or the local filesystem, enabling state to survive restarts. The server is written in Rust and designed for integration with modern AI development environments.

43 stars on GitHub. Last updated 2026-06-01. Licensed AGPL-3.0.

Use cases

• Executing JavaScript code from AI agents during conversations
• Persisting runtime state across sessions using heap snapshots
• Integrating JavaScript execution into Claude or Cursor workflows

Pros

• Written in Rust for performance and safety
• Persistent heap snapshots allow state to survive restarts
• Designed for direct integration with popular AI agents like Claude and Cursor

Cons

• Small community with only 43 stars, limited testing and support
• Requires MCP-compatible agents, not a standalone runtime
• Relies on S3 or local filesystem for snapshot storage, adding external dependencies

Indexed from awesome-mcp-servers-punkpeye and enriched against its public facts.