Plasmate
Agent-native headless browser for AI agents. Converts web pages to a Semantic Object Model (SOM) instead of raw HTML — 17x average token reduction across real-world sites (up to 117x on complex pages). Native MCP server with fetch_page, extract_text,
What is Plasmate?
Plasmate is a Model Context Protocol (MCP) server that allows AI assistants like Claude, Cursor, and VS Code to agent-native headless browser for ai agents. converts web pages to a semantic object model (som) instead of raw html — 17x average token reduction across real-world sites (up to 117x on complex pages)...
Agent-native headless browser for AI agents. Converts web pages to a Semantic Object Model (SOM) instead of raw HTML — 17x average token reduction across real-world sites (up to 117x on complex pages). Native MCP server with fetch_page, extract_text,
This server falls under the Browser Automation category on MCPgee, the world's largest MCP server directory with 33,000+ servers.
Features
- Agent-native headless browser for AI agents. Converts web pa
Use Cases
Maintainer
Works with
Installation
NPM
npx -y plasmate-mcpManual Installation
npx -y plasmate-mcpConfiguration
Configuration Details
claude_desktop_config.json
Performance
Response Metrics
Resource Usage
How to Set Up and Use Plasmate
Plasmate MCP is an agent-native headless browser server that replaces raw HTML dumps with a Semantic Object Model (SOM) — a structured, compact representation of web pages that delivers 16.6x fewer tokens on average (up to 117x on complex pages) compared to raw DOM output. It exposes six tools: fetching a page as SOM, extracting clean text, opening a persistent browser session, clicking elements by SOM ID, evaluating JavaScript, and closing sessions. AI agents in Claude Code, Claude Desktop, Cursor, and Windsurf use it to browse the web efficiently without Chrome's memory overhead.
Prerequisites
- Node.js 16 or higher (for the plasmate-mcp npm wrapper)
- Plasmate engine installed via pip, cargo, or Homebrew
- Claude Code, Claude Desktop, Cursor, Windsurf, or another MCP-compatible client
Install the plasmate-mcp npm wrapper
Install the MCP wrapper package globally so it is available via npx.
npm install -g plasmate-mcpInstall the Plasmate engine
The MCP wrapper requires the Plasmate browser engine. Install it using your preferred method.
# Option A: Python (pip)
pip install plasmate
# Option B: Rust (cargo)
cargo install plasmate
# Option C: Homebrew (macOS)
brew tap plasmate-labs/plasmate && brew install plasmateAdd to Claude Code
For Claude Code, use the mcp add command — the simplest one-liner setup.
claude mcp add plasmate -- npx plasmate-mcpAdd to Claude Desktop or Cursor
For Claude Desktop, edit claude_desktop_config.json. For Cursor, add to its MCP settings file.
{
"mcpServers": {
"plasmate": {
"command": "npx",
"args": ["-y", "plasmate-mcp"]
}
}
}Restart your MCP client and test
Restart your MCP client. Ask the AI to fetch a URL — it should use the Plasmate fetch_page tool and return a compact SOM representation instead of raw HTML.
Plasmate Examples
Client configuration
claude_desktop_config.json entry for Plasmate MCP Server using the published npm package.
{
"mcpServers": {
"plasmate": {
"command": "npx",
"args": ["-y", "plasmate-mcp"]
}
}
}Prompts to try
Example prompts that use Plasmate's SOM-based browser tools.
- "Fetch https://news.ycombinator.com and summarise the top 5 stories"
- "Extract the clean text from https://example.com/article"
- "Open https://github.com/trending and click on the first repository link"
- "Open the Hacker News homepage, then click on the first 'Ask HN' post"
- "Run this JavaScript on the open page: document.title and tell me the result"Troubleshooting Plasmate
fetch_page returns an error: 'plasmate engine not found' or 'command not found: plasmate'
The plasmate-mcp npm wrapper requires the Plasmate engine binary to be installed separately. Install it with 'pip install plasmate', 'cargo install plasmate', or 'brew install plasmate'. Ensure the binary is in your PATH by running 'plasmate --version' in your terminal.
Token output is still very large — not the expected 16x reduction
Ensure you are using the fetch_page tool (SOM output) rather than a raw HTML fetcher. If you previously had another browser MCP server configured, Claude may be using that instead. Disable other browser tools in your MCP config to ensure Plasmate is selected.
click tool fails with 'element not found by SOM ID'
SOM IDs are generated fresh on each fetch_page call and are not persistent across fetches. Always call fetch_page or open_page first to get the current SOM, then use the element IDs from that response. Do not cache or reuse SOM IDs from a previous page load.
Frequently Asked Questions about Plasmate
What is Plasmate?
Plasmate is a Model Context Protocol (MCP) server that agent-native headless browser for ai agents. converts web pages to a semantic object model (som) instead of raw html — 17x average token reduction across real-world sites (up to 117x on complex pages). native mcp server with fetch_page, extract_text, It connects AI assistants to external tools and data sources through a standardized interface.
How do I install Plasmate?
Install via npm with the command: npx -y plasmate-mcp. Then add the server configuration to your AI client's JSON config file (e.g., claude_desktop_config.json or .cursor/mcp.json).
Which AI clients work with Plasmate?
Plasmate works with all major MCP-compatible AI clients including Claude Desktop, Claude Code, Cursor, VS Code (GitHub Copilot), Windsurf, and Cline.
Is Plasmate free to use?
Yes, Plasmate is open source and available under the Apache 2.0 license. You can use it freely in both personal and commercial projects.
Plasmate Alternatives — Similar Browser Automation Servers
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