Documentation
better-playwright-mcp3
A high-performance Playwright MCP (Model Context Protocol) server with intelligent DOM compression and content search capabilities for browser automation.
Features
- 🎭 Full Playwright browser automation via MCP
- 🏗️ Client-server architecture with HTTP API
- 📍 Ref-based element identification system (
[ref=e1],[ref=e2], etc.) - 🔍 Powerful regex-based content search using ripgrep
- 💾 Persistent browser profiles with Chrome
- 🚀 91%+ DOM compression with intelligent list folding
- 📄 Semantic HTML snapshots using Playwright's internal APIs
- ⚡ High-performance search with safety limits
Installation
Global Installation (for CLI usage)
npm install -g better-playwright-mcp3Local Installation (for SDK usage)
npm install better-playwright-mcp3Usage
As a JavaScript/TypeScript SDK
Prerequisites:
1. First, start the HTTP server:
npx better-playwright-mcp3@latest server2. Then use the SDK in your code:
import { PlaywrightClient } from 'better-playwright-mcp3';
async function automateWebPage() {
// Connect to the HTTP server (must be running)
const client = new PlaywrightClient('http://localhost:3102');
// Create a page
const { pageId, success } = await client.createPage(
'my-page', // page name
'Test page', // description
'https://example.com' // URL
);
// Get page structure with intelligent folding
const outline = await client.getOutline(pageId);
console.log(outline);
// Returns compressed outline (~90% reduction) with list folding
// Search for specific content (regex by default)
const searchResult = await client.searchSnapshot(pageId, 'Example', { ignoreCase: true });
console.log(searchResult);
// Search with regular expressions (default behavior)
const prices = await client.searchSnapshot(pageId, '\\$[0-9]+\\.\\d{2}', { lineLimit: 10 });
// Search multiple patterns (OR)
const links = await client.searchSnapshot(pageId, 'link|button|input', { ignoreCase: true });
// Interact with the page using ref identifiers
await client.browserClick(pageId, 'e3'); // Click element
await client.browserType(pageId, 'e4', 'Hello World'); // Type text
await client.browserHover(pageId, 'e2'); // Hover over element
// Navigation
await client.browserNavigate(pageId, 'https://google.com');
await client.browserNavigateBack(pageId);
await client.browserNavigateForward(pageId);
// Scrolling
await client.scrollToBottom(pageId);
await client.scrollToTop(pageId);
// Waiting
await client.waitForTimeout(pageId, 2000); // Wait 2 seconds
await client.waitForSelector(pageId, 'body');
// Take screenshots
const screenshot = await client.screenshot(pageId, true); // Full page
// Clean up
await client.closePage(pageId);
}Available Methods:
- Page Management:
createPage,closePage,listPages - Navigation:
browserNavigate,browserNavigateBack,browserNavigateForward - Interaction:
browserClick,browserType,browserHover,browserSelectOption,fill - Advanced Actions:
browserPressKey,browserFileUpload,browserHandleDialog - Page Structure:
getOutline- Get intelligently compressed page structure with list folding (NEW in v3.2.0) - Content Search:
searchSnapshot- Search page content with regex patterns (powered by ripgrep) - Screenshots:
screenshot- Capture page as image - Scrolling:
scrollToBottom,scrollToTop - Waiting:
waitForTimeout,waitForSelector
MCP Server Mode
The MCP server requires an HTTP server to be running. You need to start both:
Step 1: Start the HTTP server
npx better-playwright-mcp3@latest serverStep 2: In another terminal, start the MCP server
npx better-playwright-mcp3@latestThe MCP server will:
1. Start listening on stdio for MCP protocol messages
2. Connect to the HTTP server on port 3102
3. Route browser automation commands through the HTTP server
Standalone HTTP Server Mode
You can run the HTTP server independently:
npx better-playwright-mcp3@latest serverOptions:
-p, --port- Server port (default: 3102)--host- Server host (default: localhost)--headless- Run browser in headless mode--chromium- Use Chromium instead of Chrome--no-user-profile- Do not use persistent user profile--user-data-dir- User data directory
MCP Tools
When used with AI assistants, the following tools are available:
Page Management
createPage- Create a new browser page with name and descriptionclosePage- Close a specific pagelistPages- List all managed pages with titles and URLs
Browser Actions
browserClick- Click an element using its ref identifierbrowserType- Type text into an elementbrowserHover- Hover over an elementbrowserSelectOption- Select options in a dropdownbrowserPressKey- Press keyboard keysbrowserFileUpload- Upload files to file inputbrowserHandleDialog- Handle browser dialogs (alert, confirm, prompt)browserNavigate- Navigate to a URLbrowserNavigateBack- Go back to previous pagebrowserNavigateForward- Go forward to next pagescrollToBottom- Scroll to bottom of page/elementscrollToTop- Scroll to top of page/elementwaitForTimeout- Wait for specified millisecondswaitForSelector- Wait for element to appear
Content Search & Screenshots
searchSnapshot- Search page content using regex patterns (powered by ripgrep)screenshot- Take a screenshot (PNG/JPEG)
Architecture
Intelligent DOM Compression (NEW in v3.2.0)
The outline generation uses a three-step compression algorithm:
1. Unwrap - Remove meaningless generic wrapper nodes
2. Text Truncation - Limit text content to 50 characters
3. List Folding - Detect and compress repetitive patterns using SimHash
Original DOM (5000+ lines)
↓
[Remove empty wrappers]
↓
[Detect similar patterns]
↓
Compressed Outline ( MCP Server HTTP Server Browser
|
v
ripgrep engineKey Design Principles
- Minimal Token Usage: Intelligent compression reduces DOM by ~91%
- On-Demand Search: Content retrieved via regex patterns when needed
- Performance: Uses ripgrep for 10x+ faster searching
- Safety: Automatic result limiting to prevent context overflow
Ref-Based Element System
Elements in snapshots are identified using ref attributes (e.g., [ref=e1], [ref=e2]). This system:
- Provides stable identifiers for elements
- Works with Playwright's internal
aria-refselectors - Enables precise element targeting across page changes
Example snapshot:
- generic [ref=e2]:
- heading "Example Domain" [level=1] [ref=e3]
- paragraph [ref=e4]: This domain is for use in illustrative examples
- link "More information..." [ref=e5] [cursor=pointer]Examples
Creating and Navigating Pages
// Create a page
const { pageId, success } = await client.createPage(
'shopping',
'Amazon shopping page',
'https://amazon.com'
);
// Navigate to another URL
await client.browserNavigate(pageId, 'https://google.com');
// Go back/forward
await client.browserNavigateBack(pageId);
await client.browserNavigateForward(pageId);Getting Page Structure (Enhanced in v3.2.0)
// Get intelligently compressed page outline
const outline = await client.getOutline(pageId);
console.log(outline);
// Example output showing list folding:
// Page Outline (473/5257 lines):
// - banner [ref=e1]
// - navigation [ref=e2]
// - list "Products" [ref=e3]
// - listitem "Product 1" [ref=e4]
// - listitem (... and 47 more similar) [refs: e5, e6, ...]
//
// Compression: 91% reduction while preserving all refsSearching Content
// Search for text (case insensitive)
const results = await client.searchSnapshot(pageId, 'product', { ignoreCase: true });
// Search with regular expression (default behavior)
const emails = await client.searchSnapshot(pageId, '[a-zA-Z0-9]+@[a-zA-Z0-9]+\\.[a-z]+');
// Search multiple patterns (OR)
const buttons = await client.searchSnapshot(pageId, 'button|submit|click', { ignoreCase: true });
// Search for prices with dollar sign
const prices = await client.searchSnapshot(pageId, '\\$\\d+\\.\\d{2}');
// Limit number of result lines
const firstTen = await client.searchSnapshot(pageId, 'item', { lineLimit: 10 });Search Options:
pattern(required) - Regex pattern to search forignoreCase(optional) - Case insensitive search (default: false)lineLimit(optional) - Maximum lines to return (default: 100, max: 100)
Response Format:
result- Matched text contentmatchCount- Total number of matches foundtruncated- Whether results were truncated due to line limit
Interacting with Elements
// Click on element using its ref identifier
await client.browserClick(pageId, 'e3');
// Type text into input field
await client.browserType(pageId, 'e4', 'search query');
// Hover over element
await client.browserHover(pageId, 'e2');
// Press keyboard key
await client.browserPressKey(pageId, 'Enter');Scrolling and Waiting
// Scroll page
await client.scrollToBottom(pageId);
await client.scrollToTop(pageId);
// Wait operations
await client.waitForTimeout(pageId, 2000); // Wait 2 seconds
await client.waitForSelector(pageId, '#my-element');Best Practices for AI Assistants
Recommended Workflow: Outline First, Then Precise Actions
When using this library with AI assistants, follow this optimized workflow for maximum efficiency:
1. Start with Page Outline (Always First Step)
// Always begin by getting the compressed page structure
const outline = await client.getOutline(pageId);
// Returns intelligently compressed view with ~91% reductionThe outline provides:
- Complete page structure with intelligent list folding
- First element of each pattern preserved as sample
- All ref identifiers for precise element targeting
- Clear indication of repetitive patterns (e.g., "... and 47 more similar")
2. Use Outline to Guide Precise Searches
// Based on outline understanding, perform targeted searches
const searchResults = await client.searchSnapshot(pageId, 'specific term', {
ignoreCase: true,
lineLimit: 10
});
// Now you know exactly what to search for and where it might be3. Take Actions with Verified Ref IDs
// Use ref IDs discovered from outline or grep, not guesswork
await client.browserClick(pageId, 'e42'); // Ref ID confirmed from outlineWhy This Approach?
Token Efficiency: Compressed outline (typically = 18.0.0
- TypeScript
- Chrome or Chromium browser
Building from Source
# Clone the repository
git clone https://github.com/yourusername/better-playwright-mcp.git
cd better-playwright-mcp
# Install dependencies
npm install
# Build the project
npm run build
# Run in development mode
npm run devProject Structure
better-playwright-mcp3/
├── src/
│ ├── index.ts # Main export file
│ ├── mcp-server.ts # MCP server implementation
│ ├── client/
│ │ └── playwright-client.ts # HTTP client for browser automation
│ ├── server/
│ │ └── playwright-server.ts # HTTP server controlling browsers
│ └── utils/
│ ├── smart-outline-simple.ts # Intelligent outline generation
│ ├── list-detector.ts # Pattern detection using SimHash
│ ├── dom-simhash.ts # SimHash implementation
│ └── remove-useless-wrappers.ts # DOM cleanup
├── bin/
│ └── cli.js # CLI entry point
├── docs/
│ └── architecture.md # Detailed architecture documentation
├── package.json
├── tsconfig.json
└── README.mdTroubleshooting
Common Issues
1. Port already in use
- Change the port using
-pflag:npx better-playwright-mcp3 server -p 3103 - Or set environment variable:
PORT=3103 npx better-playwright-mcp3 server
2. Browser not launching
- Ensure Chrome or Chromium is installed
- Try using
--chromiumflag for Chromium - Check system resources
3. Element not found
- Verify the ref identifier exists in outline
- Use
searchSnapshot()to search for elements - Wait for elements using
waitForSelector()
4. Search returns too many results
- Use more specific patterns
- Use
lineLimitoption to limit results - Leverage regex features for precise matching
Debug Mode
Enable detailed logging:
DEBUG=* npx better-playwright-mcp3Contributing
Contributions are welcome! Please feel free to submit a Pull Request.
License
MIT
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