Plasmate

io.github.plasmate-labsPublished by GitHub account plasmate-labsv0.4.1Updated Oct 24, 2026

Browser engine for AI agents. HTML in, Semantic Object Model out. 16x fewer tokens.

VerifiedSTDIODesktop onlyWeb Search & ScrapingBrowser Automation

Overview

AI-generated overview

Lets an assistant browse web pages through the Plasmate engine, returning a compact Semantic Object Model instead of raw HTML.

What you can do
Plasmate is a browser engine for AI agents exposed as an MCP server. It provides tools to fetch a URL and return a Semantic Object Model (SOM), extract clean readable text from a URL, open a persistent browser session, click elements by SOM ID, execute JavaScript in the page, and close the session. Output is structured JSON rather than raw HTML, which the README says uses far fewer tokens than DOM dumps.
When to use it
Useful when an assistant needs to read or interact with web pages while keeping context small, for example fetching page content, extracting article text, or driving a lightweight browser session for clicks and script evaluation. It is an alternative to a full Chrome-based browser for agent workflows.
Requirements
Runs locally over stdio as an npm package (plasmate-mcp), typically launched with npx. The README says the Plasmate engine itself must also be installed separately, via pip, cargo, or Homebrew. No authentication, environment variables, or headers are declared. Desktop only; not a web executable.
Before you install
The evaluate tool executes JavaScript in the page, and click and open_page act on live sites, so sessions can trigger real page actions. Fetching arbitrary URLs sends those requests to third parties. The README mentions a separate Chrome cookie export extension in the ecosystem, but this server declares no credentials of its own.

Installation

In SourceWeft

  1. Open Plasmate in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Desktop only via STDIO. STDIO servers start a local process, so they need the SourceWeft desktop host.

Other MCP clients

Follow the launch instructions in the repository.

README

plasmate-mcp

MCP server for Plasmate - the browser engine for AI agents.

Gives Claude Code, Claude Desktop, Cursor, Windsurf, and any MCP client the ability to browse the web through Plasmate instead of Chrome.

Install

bash
# Install the MCP wrappernpm install -g plasmate-mcp
# Install the Plasmate engine (pick one)pip install plasmate# or: cargo install plasmate# or: brew tap plasmate-labs/plasmate && brew install plasmate

Use with Claude Code

bash
claude mcp add plasmate -- npx plasmate-mcp

Or manually add to ~/.claude/settings.json:

json
{  "mcpServers": {    "plasmate": {      "command": "npx",      "args": ["-y", "plasmate-mcp"]    }  }}

Use with Claude Desktop

Add to claude_desktop_config.json:

json
{  "mcpServers": {    "plasmate": {      "command": "npx",      "args": ["-y", "plasmate-mcp"]    }  }}

Use with Cursor

Add to Cursor's MCP settings:

json
{  "mcpServers": {    "plasmate": {      "command": "npx",      "args": ["-y", "plasmate-mcp"]    }  }}

This repo is also a Cursor plugin (.cursor-plugin/plugin.json + mcp.json). Test locally by copying it to ~/.cursor/plugins/local/plasmate. Submit the public repo at cursor.com/marketplace/publish.

Available Tools

Once connected, your AI gets these tools:

ToolDescription
fetch_pageFetch a URL and get the Semantic Object Model (SOM)
extract_textGet clean readable text from any URL
open_pageOpen a persistent browser session
clickClick elements by SOM ID
evaluateExecute JavaScript in the page
close_pageClose a browser session

Why Plasmate instead of Chrome?

  • 16.6x fewer tokens - SOM is dramatically smaller than DOM dumps
  • 50x faster - No rendering engine overhead
  • 30MB memory - vs Chrome's 300MB+
  • Structured output - Clean JSON, not raw HTML

Links

Part of the Plasmate Ecosystem

Engineplasmate - The browser engine for agents
MCPplasmate-mcp - Claude Code, Cursor, Windsurf
Extensionplasmate-extension - Chrome cookie export
SDKsPython / Node.js / Go / Rust
FrameworksLangChain / CrewAI / AutoGen / Smolagents
ToolsScrapy / Audit / A11y / GitHub Action
ResourcesAwesome Plasmate / Notebooks / Benchmarks
Docsdocs.plasmate.app
W3CWeb Content Browser for AI Agents

Source: README.md at commit 06b868e

Tools

0
SourceWeft has not started this package in its sandbox yet, so its tools are not known.

Version history

1
  1. v0.4.1LatestSep 16, 2026

Score

50% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 days25 pts

    Keep the endpoint answering the MCP handshake; SourceWeft probes it every 30 days.

  • Auth declared10 pts

    Declare the credential headers in the registry entry, or keep the endpoint answering the probe so its auth can be classified.

  • Tools listed15 pts

    Answer tools/list without a credential, or ship a package that starts in a sandbox without one.

  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts