Should I use BeautifulSoup with lxml or html.parser?
BeautifulSoup supports multiple parsers, each with tradeoffs.
lxml (recommended for most cases):
- Fastest parser available
- Handles malformed HTML well
- Requires external C dependencies (may complicate deployment)
- Use:
BeautifulSoup(html, 'lxml')
html.parser (built-in):
- Part of Python standard library (no extra dependencies)
- Slower than lxml but still reasonable for small to medium documents
- More lenient with malformed HTML than lxml in some cases
- Use:
BeautifulSoup(html, 'html.parser')
html5lib (strictest):
- Parses HTML exactly like a browser would
- Slowest option
- Best for: Sites with complex, modern HTML5 markup
- Use:
BeautifulSoup(html, 'html5lib')
Performance comparison:
For a typical webpage:
- lxml: ~0.05 seconds
- html.parser: ~0.2 seconds
- html5lib: ~1 second
Recommendation:
Use lxml for production scrapers where performance matters. Use html.parser for simple scripts or when you can't install dependencies. Avoid html5lib unless you specifically need strict HTML5 parsing.
Installation:
pip install beautifulsoup4 lxml
Always specify the parser explicitly to ensure consistent behavior across environments.