🕷️ Crawailer

The JavaScript-first web scraper that actually works with modern websites

Finally! A Python library that handles React, Vue, Angular, and dynamic content without the headaches. When requests fails and Selenium feels like overkill, Crawailer delivers clean, AI-ready content extraction with bulletproof JavaScript execution.

⚡ Perfect for Claude Code MCP servers - Built specifically for AI agents and MCP integration

pip install crawailer

✨ Features

• 🎯 JavaScript-First: Executes real JavaScript on React, Vue, Angular sites (unlike requests)
• ⚡ Lightning Fast: 5-10x faster HTML processing with C-based selectolax
• 🤖 AI-Optimized: Clean markdown output perfect for LLM training and RAG
• 🔧 Claude Code Ready: Drop-in MCP server integration for AI agents
• 📦 Zero Config: Works immediately with sensible defaults
• 🧪 Battle-Tested: 18 comprehensive test suites with 70+ real-world scenarios
• 🎨 Developer Joy: Rich terminal output, helpful errors, progress tracking

🚀 Quick Start

import crawailer as web

# Simple content extraction
content = await web.get("https://example.com")
print(content.markdown)  # Clean, LLM-ready markdown
print(content.text)      # Human-readable text
print(content.title)     # Extracted title

# JavaScript execution for dynamic content
content = await web.get(
    "https://spa-app.com",
    script="document.querySelector('.dynamic-price').textContent"
)
print(f"Price: {content.script_result}")

# Batch processing with JavaScript
results = await web.get_many(
    ["url1", "url2", "url3"],
    script="document.title + ' | ' + document.querySelector('.description')?.textContent"
)
for result in results:
    print(f"{result.title}: {result.script_result}")

# Smart discovery with interaction
research = await web.discover(
    "AI safety papers", 
    script="document.querySelector('.show-more')?.click()",
    max_pages=10
)
# Returns the most relevant content with enhanced extraction

# Compare: Traditional scraping fails on modern sites
# requests.get("https://react-app.com") → Empty <div id="root"></div>
# Crawailer → Full content + dynamic data

🧠 Claude Code MCP Integration

# Add to your Claude Code MCP server
from crawailer.mcp import create_mcp_server

@mcp_tool("web_extract")
async def extract_content(url: str, script: str = ""):
    """Extract content from any website with optional JavaScript execution"""
    content = await web.get(url, script=script)
    return {
        "title": content.title,
        "markdown": content.markdown,
        "script_result": content.script_result,
        "word_count": content.word_count
    }

# Now Claude can extract content from ANY website, including SPAs!

🎯 Design Philosophy

For Robots, By Humans

• Predictive: Anticipates what you need and provides it
• Forgiving: Handles errors gracefully with helpful suggestions
• Efficient: Fast by default, with smart caching and concurrency
• Composable: Small, focused functions that work well together

Perfect for AI Workflows

• LLM-Optimized: Clean markdown, structured data, semantic chunking
• Context-Aware: Extracts relationships and metadata automatically
• Quality-Focused: Built-in content quality assessment
• Archive-Ready: Designed for long-term storage and retrieval

📖 Use Cases

🤖 AI Agents & LLM Applications

Problem: Training data scattered across JavaScript-heavy academic sites

# Research assistant workflow with JavaScript interaction
research = await web.discover(
    "quantum computing breakthroughs",
    script="document.querySelector('.show-abstract')?.click(); return document.querySelector('.full-text')?.textContent"
)
for paper in research:
    # Rich content includes JavaScript-extracted data
    summary = await llm.summarize(paper.markdown)
    dynamic_content = paper.script_result  # JavaScript execution result
    insights = await llm.extract_insights(paper.content + dynamic_content)

🛒 E-commerce Price Monitoring

Problem: Product prices loaded via AJAX, requests sees loading spinners

# Monitor competitor pricing with dynamic content
products = await web.get_many(
    competitor_urls,
    script="return {price: document.querySelector('.price')?.textContent, stock: document.querySelector('.inventory')?.textContent}"
)
for product in products:
    if product.script_result['price'] != cached_price:
        await alert_price_change(product.url, product.script_result)

🔗 MCP Servers

Problem: Claude needs reliable web content extraction tools

# Easy MCP integration (with crawailer[mcp])
from crawailer.mcp import create_mcp_server

server = create_mcp_server()
# Automatically exposes web.get, web.discover, etc. as MCP tools

📊 Social Media & Content Analysis

Problem: Posts and comments load infinitely via JavaScript

# Extract social media discussions with infinite scroll
content = await web.get(
    "https://social-platform.com/topic/ai-safety",
    script="window.scrollTo(0, document.body.scrollHeight); return document.querySelectorAll('.post').length"
)
# Gets full thread content, not just initial page load

🛠️ Installation

# Basic installation
pip install crawailer

# With AI features (semantic search, entity extraction)
pip install crawailer[ai]

# With MCP server capabilities  
pip install crawailer[mcp]

# Everything
pip install crawailer[all]

# Post-install setup (installs Playwright browsers)
crawailer setup

🏗️ Architecture

Crawailer is built on modern, focused libraries:

• 🎭 Playwright: Reliable browser automation
• ⚡ selectolax: 5-10x faster HTML parsing (C-based)
• 📝 markdownify: Clean HTML→Markdown conversion
• 🧹 justext: Intelligent content extraction and cleaning
• 🔄 httpx: Modern async HTTP client

🧪 Battle-Tested Quality

Crawailer includes 18 comprehensive test suites with real-world scenarios:

• Modern Frameworks: React, Vue, Angular demos with full JavaScript APIs
• Mobile Compatibility: Safari iOS, Chrome Android, responsive designs
• Production Edge Cases: Network failures, memory pressure, browser differences
• Performance Testing: Stress tests, concurrency, resource management

Want to contribute? We welcome PRs with new test scenarios! Our test sites library shows exactly how different frameworks should behave with JavaScript execution.

📝 Future TODO: Move examples to dedicated repository for community contributions

🤝 Perfect for MCP Projects

MCP servers love Crawailer because it provides:

• Focused tools: Each function does one thing well
• Rich outputs: Structured data ready for LLM consumption
• Smart defaults: Works out of the box with minimal configuration
• Extensible: Easy to add domain-specific extraction logic

# Example MCP server tool
@mcp_tool("web_research")
async def research_topic(topic: str, depth: str = "comprehensive"):
    results = await web.discover(topic, max_pages=20)
    return {
        "sources": len(results),
        "content": [r.summary for r in results],
        "insights": await analyze_patterns(results)
    }

🥊 Crawailer vs Traditional Tools

Challenge	requests & HTTP libs	Selenium	Crawailer
React/Vue/Angular	❌ Empty templates	🟡 Slow, complex setup	✅ Just works
Dynamic Pricing	❌ Shows loading spinner	🟡 Requires waits/timeouts	✅ Intelligent waiting
JavaScript APIs	❌ No access	🟡 Clunky WebDriver calls	✅ Native page.evaluate()
Speed	🟢 100-500ms	❌ 5-15 seconds	✅ 2-5 seconds
Memory	🟢 1-5MB	❌ 200-500MB	🟡 100-200MB
AI-Ready Output	❌ Raw HTML	❌ Raw HTML	✅ Clean Markdown
Developer Experience	🟡 Manual parsing	❌ Complex WebDriver	✅ Intuitive API

The bottom line: When JavaScript matters, Crawailer delivers. When it doesn't, use requests.

📖 See complete tool comparison → (includes Scrapy, Playwright, BeautifulSoup, and more)

🎉 What Makes It Delightful

JavaScript-Powered Intelligence

# Dynamic content extraction from SPAs
content = await web.get(
    "https://react-app.com",
    script="window.testData?.framework + ' v' + window.React?.version"
)
# Automatically detects: React application with version info
# Extracts: Dynamic content + framework details

# E-commerce with JavaScript-loaded prices
product = await web.get(
    "https://shop.com/product",
    script="document.querySelector('.dynamic-price')?.textContent",
    wait_for=".price-loaded"
) 
# Recognizes product page with dynamic pricing
# Extracts: Real-time price, reviews, availability, specs

Beautiful Output

✨ Found 15 high-quality sources
📊 Sources: 4 arxiv, 3 journals, 2 conferences, 6 blogs  
📅 Date range: 2023-2024 (recent research)
⚡ Average quality score: 8.7/10
🔍 Key topics: transformers, safety, alignment

Helpful Errors

try:
    content = await web.get("problematic-site.com")
except web.CloudflareProtected:
    # "💡 Try: await web.get(url, stealth=True)"
except web.PaywallDetected as e:
    # "🔍 Found archived version: {e.archive_url}"

📚 Documentation

• Tool Comparison: How Crawailer compares to Scrapy, Selenium, BeautifulSoup, etc.
• Getting Started: Installation and first steps
• JavaScript API: Complete JavaScript execution guide
• API Reference: Complete function documentation
• Benchmarks: Performance comparison with other tools
• MCP Integration: Building MCP servers with Crawailer
• Examples: Real-world usage patterns
• Architecture: How Crawailer works internally

🤝 Contributing

We love contributions! Crawailer is designed to be:

• Easy to extend: Add new content extractors and browser capabilities
• Well-tested: Comprehensive test suite with real websites
• Documented: Every feature has examples and use cases

See CONTRIBUTING.md for details.

📄 License

MIT License - see LICENSE for details.

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🚀 Ready to Stop Fighting JavaScript?

pip install crawailer
crawailer setup  # Install browser engines

Join the revolution: Stop losing data to requests.get() failures. Start extracting real content from real websites that actually use JavaScript.

⭐ Star us on GitHub if Crawailer saves your scraping sanity!

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Built with ❤️ for the age of AI agents and automation

Crawailer: Because robots deserve delightful web experiences too 🤖✨