langchain-crw 0.4.0

LangChain integration for CRW — high-performance web scraping document loader

langchain-crw

LangChain document loader for CRW — a high-performance, Firecrawl-compatible web scraper written in Rust.

Installation

pip install langchain-crw
# or
uv add langchain-crw

That's it. No server to install, no cargo install, no Docker. The crw SDK automatically downloads and manages the CRW binary for you.

Quick Start — Zero Config (Subprocess Mode)

from langchain_crw import CrwLoader

# Just works — crw SDK handles everything locally
loader = CrwLoader(url="https://example.com", mode="scrape")
docs = loader.load()
print(docs[0].page_content)  # clean markdown

Cloud Mode (fastcrw.com)

No local binary needed. Sign up at fastcrw.com and get 500 free credits:

from langchain_crw import CrwLoader

loader = CrwLoader(
    url="https://example.com",
    mode="scrape",
    api_url="https://fastcrw.com/api",
    api_key="crw_live_...",  # or set CRW_API_KEY env var
)
docs = loader.load()

Advanced: Self-hosted Server

If you prefer running a persistent CRW server (e.g., shared across services):

# Option A: Install binary
curl -fsSL https://raw.githubusercontent.com/us/crw/main/install.sh | sh
crw  # starts on http://localhost:3000

# Option B: Docker
docker run -d -p 3000:3000 ghcr.io/us/crw:latest

loader = CrwLoader(url="https://example.com", api_url="http://localhost:3000")

Usage

Scrape a single page

loader = CrwLoader(url="https://example.com", mode="scrape")
docs = loader.load()

print(docs[0].page_content)    # clean markdown
print(docs[0].metadata)        # {'title': '...', 'sourceURL': '...', 'statusCode': 200}

Crawl an entire site

loader = CrwLoader(
    url="https://docs.example.com",
    mode="crawl",
    params={"max_depth": 3, "max_pages": 50},
)
docs = loader.load()
print(f"Crawled {len(docs)} pages")

Discover URLs (map mode)

loader = CrwLoader(url="https://example.com", mode="map")
urls = [doc.page_content for doc in loader.load()]

Search the web (Cloud Only)

Cloud-only feature. Search requires a fastcrw.com API key or a CRW server with search configured.

from langchain_crw import CrwLoader

loader = CrwLoader(
    query="web scraping tools 2026",
    mode="search",
    api_url="https://fastcrw.com/api",
    api_key="YOUR_KEY",
    params={"limit": 5},
)
docs = loader.load()

for doc in docs:
    print(doc.metadata["title"], doc.metadata["url"])
    print(doc.page_content[:200])

Scrape with JS rendering

loader = CrwLoader(
    url="https://spa-app.example.com",
    mode="scrape",
    params={
        "render_js": True,
        "wait_for": 3000,
        "css_selector": "article.main-content",
    },
)
docs = loader.load()

RAG pipeline

from langchain_crw import CrwLoader
from langchain_openai import OpenAIEmbeddings
from langchain_community.vectorstores import FAISS
from langchain_text_splitters import RecursiveCharacterTextSplitter

# Crawl docs (self-hosted or cloud — same code)
loader = CrwLoader(url="https://docs.example.com", mode="crawl", params={"max_depth": 3, "max_pages": 50})
docs = loader.load()

# Split and embed
splitter = RecursiveCharacterTextSplitter(chunk_size=1000, chunk_overlap=200)
chunks = splitter.split_documents(docs)
vectorstore = FAISS.from_documents(chunks, OpenAIEmbeddings())

# Query
results = vectorstore.similarity_search("how to authenticate")

Configuration

Constructor

Parameter	Type	Default	Description
url	str	""	URL to scrape, crawl, or map. Not required for search mode
api_key	str | None	None	Bearer token. Falls back to CRW_API_KEY env var
api_url	str | None	None	CRW server URL. Falls back to CRW_API_URL. If unset, uses subprocess mode (no server needed)
mode	"scrape" | "crawl" | "map" | "search"	"scrape"	Operation mode
query	str | None	None	Search query string. Required for search mode
params	dict | None	None	Additional API parameters

Params (snake_case, auto-converted to camelCase)

Param	Modes	Description
render_js	scrape	Enable JavaScript rendering
wait_for	scrape	Wait time in ms after page load
css_selector	scrape	CSS selector to extract
only_main_content	scrape, crawl	Extract main content only
max_depth	crawl, map	Maximum crawl depth
max_pages	crawl	Maximum pages to crawl
use_sitemap	map	Use sitemap for URL discovery
poll_interval	crawl	Poll interval in seconds (default: 2)
timeout	crawl	Crawl timeout in seconds (default: 300)

Migrating from FireCrawlLoader

CrwLoader supports the same scrape, crawl, and map modes, plus a search mode. Note that CrwLoader defaults to mode="scrape" while FireCrawlLoader defaults to mode="crawl" — set the mode explicitly when migrating.

# Before
from langchain_community.document_loaders import FireCrawlLoader
loader = FireCrawlLoader(url="https://example.com", api_key="fc-...", mode="scrape")

# After — pip install langchain-crw, zero config, no server needed
from langchain_crw import CrwLoader
loader = CrwLoader(url="https://example.com", mode="scrape")

License

MIT