Web scrapers extract data from websites to use programmatically. To access and parse HTML, they rely on parser libraries like lxml and BeautifulSoup. But which one is better suited for web scraping?
Both have strengths that make them popular choices:
Speed
lxml parses HTML extremely quickly using Python bindings to C libraries libxml2 and libxslt. This makes it faster than pure Python alternatives.
BeautifulSoup also parses quickly, but relies entirely on Python. lxml has the edge in raw performance.
Convenience
BeautifulSoup shines for convenience - its API is designed for easy HTML traversal:
soup = BeautifulSoup(html, 'html.parser')
links = soup.find_all('a')lxml is focused on XML/HTML itself rather than traversal, so accessing elements is a bit more verbose:
tree = lxml.html.fromstring(html)
links = tree.xpath('//a') Invalid HTML
Websites often have malformed HTML that trips up parsers.
BeautifulSoup gracefully handles bad HTML with its forgiving parser. It can parse nearly any HTML.
lxml fails fast on invalid markup. This makes it less tolerant, but faster when HTML is valid.
Scraping Javascript Sites
Many sites rely heavily on Javascript to render content. Since web scrapers only see raw HTML, they miss dynamically loaded content.
Neither library executes Javascript, so scrapers need browser automation tools like Selenium for complex dynamic sites.
Verdict
For high performance and validity, use lxml. For convenience and resilience, use BeautifulSoup. Evaluate their tradeoffs against your specific web scraping needs.
The best approach may be to use both - lxml for speed and BeautifulSoup to smooth over bad HTML.