crawl4ai

High-performance web crawler with intelligent chunking. Crawls web pages and extracts content as markdown using LLM-based skeleton planning.

Commands

crawl_url (alias: webCrawl)

Crawl a web page with native workflow execution and LLM-based intelligent chunking.

Parameters:

Parameter	Type	Default	Description
url	str	-	Target URL to crawl (required)
action	str	"smart"	Action mode: "smart", "skeleton", "crawl"
fit_markdown	bool	true	Clean and simplify markdown output
max_depth	int	0	Maximum crawling depth (0=single page)
return_skeleton	bool	false	Also return document skeleton (TOC)
chunk_indices	list[int]	-	List of section indices to extract

Action Modes:

Mode	Description	Use Case
smart (default)	LLM generates chunk plan, then extracts relevant sections	Large docs where you need specific info
skeleton	Extract lightweight TOC without full content	Quick overview, decide what to read
crawl	Return full markdown content	Small pages, complete content needed

Runtime Transport:

• max_depth = 0: Uses HTTP strategy (no browser cold-start) for lower latency.
• max_depth > 0: Uses browser deep-crawl strategy (BFS) for multi-page traversal.
• file://... with max_depth = 0: Uses local fast-path (no crawl4ai runtime bootstrap) for deterministic fixture/local-note benchmarking.
• Persistent worker mode reuses the HTTP crawler instance across requests to reduce repeated initialization cost.

Examples:

# Smart crawl with LLM chunking (default)
tool: `crawl4ai.CrawlUrl` with `{"url": "https://example.com"}`

# Skeleton only - get TOC quickly
tool: `crawl4ai.CrawlUrl` with `{"url": "https://example.com", "action": "skeleton"}`

# Full content crawl
tool: `crawl4ai.CrawlUrl` with `{"url": "https://example.com", "action": "crawl"}`

# Extract specific sections
tool: `crawl4ai.CrawlUrl` with `{"url": "https://example.com", "chunk_indices": [0, 1, 2]}`

# Deep crawl (follow links up to depth N)
tool: `crawl4ai.CrawlUrl` with `{"url": "https://example.com", "max_depth": 2}`

# Get skeleton with full content
tool: `crawl4ai.CrawlUrl` with `{"url": "https://example.com", "return_skeleton": true}`

Core Concepts

Topic	Description	Reference
Skeleton Planning	LLM sees TOC (~500 tokens) not full content (~10k+)	smart-chunking.md
Chunk Extraction	Token-aware section extraction	chunking.md
Deep Crawling	Multi-page crawling with BFS strategy	deep-crawl.md

Best Practices

• Use skeleton mode first for large documents to understand structure
• Use chunk_indices to extract specific sections instead of full content
• Set max_depth > 0 carefully - limits pages crawled to prevent runaway crawling
• Keep fit_markdown=true for cleaner output, false for raw content

Advanced

• Batch multiple URLs with separate calls
• Combine with knowledge tools for RAG pipelines
• Use skeleton + LLM to auto-generate chunk plans for custom extraction