| name | beautifulsoup4 |
| description | Parse, search, and modify HTML/XML documents by building a navigable tree of tags and text. |
| version | 4.14.3 |
| ecosystem | python |
| license | MIT License |
| generated_with | gpt-5.2 |
Imports
import bs4
from bs4 import BeautifulSoup, Tag, Comment
from bs4.exceptions import FeatureNotFound, ParserRejectedMarkup
from bs4.dammit import UnicodeDammit
Core Patterns
Parse markup with an explicit parser ✅ Current
from __future__ import annotations
from bs4 import BeautifulSoup
html_doc = "<html><body><p class='body strikeout'>Hello</p></body></html>"
soup = BeautifulSoup(html_doc, "html.parser")
p = soup.find("p")
assert p is not None
print(p.name)
print(p.get_text())
- Prefer
BeautifulSoup(markup, "html.parser"), "lxml", "html5lib", or "xml"/"lxml-xml" depending on your needs; different parsers can produce different trees for invalid documents.
Parse from a file handle (context manager) ✅ Current
from __future__ import annotations
from pathlib import Path
from bs4 import BeautifulSoup
path = Path("example.html")
path.write_text("<html><body><a href='/x'>Link</a></body></html>", encoding="utf-8")
with path.open("r", encoding="utf-8") as fp:
soup = BeautifulSoup(fp, "html.parser")
a = soup.find("a")
assert a is not None
print(a.get("href"))
- Pass an open file handle directly to
BeautifulSoup to let the builder stream/handle encodings appropriately.
Find elements and navigate relatives ✅ Current
from __future__ import annotations
from typing import Optional
from bs4 import BeautifulSoup, Tag
html_doc = """
<div id="root">
<h1>Title</h1>
<p>First</p>
<p>Second <span>inner</span></p>
</div>
"""
soup = BeautifulSoup(html_doc, "html.parser")
root: Optional[Tag] = soup.find(id="root")
assert root is not None
h1: Optional[Tag] = root.find("h1")
assert h1 is not None
second_p: Optional[Tag] = h1.find_next("p")
assert second_p is not None
print(second_p.get_text(strip=True))
all_ps = root.find_all("p")
print([p.get_text(" ", strip=True) for p in all_ps])
- Use
find, find_all, and the find_next* / find_previous* / sibling / parent variants for tree navigation.
Work with tag attributes (including multi-valued class) ✅ Current
from __future__ import annotations
from bs4 import BeautifulSoup, Tag
soup = BeautifulSoup("<p id='x' class='body strikeout'></p>", "html.parser")
p = soup.find("p")
assert isinstance(p, Tag)
print(p["id"])
print(p.get("id"))
print(p["class"])
print(p.get_attribute_list("id"))
print(p.get_attribute_list("class"))
p["data-role"] = "demo"
del p["id"]
print(p.attrs)
- In HTML mode,
class, rel, etc. are typically stored as list[str]. Use Tag.get_attribute_list(name) to normalize to a list.
Handle text nodes and comments safely ✅ Current
from __future__ import annotations
from bs4 import BeautifulSoup, Comment
from bs4.element import NavigableString
soup = BeautifulSoup("<p>Hello<!--secret--></p>", "html.parser")
p = soup.find("p")
assert p is not None
comment = p.find(string=lambda s: isinstance(s, Comment))
assert isinstance(comment, Comment)
print(comment)
text = p.find(string=lambda s: isinstance(s, NavigableString) and not isinstance(s, Comment))
assert isinstance(text, NavigableString)
text.replace_with("Hi")
print(p.get_text())
- Treat
NavigableString as immutable; use replace_with(...) to change text.
Configuration
- Parser selection (
features):
"html.parser": built-in, decent baseline."lxml": fast (requires lxml)."html5lib": most lenient (slow; requires html5lib)."xml" / "lxml-xml": XML parsing mode (attribute handling differs from HTML).
parse_only: pass a SoupStrainer (not covered here) to parse only parts of a document for speed/memory.from_encoding / exclude_encodings: hint or restrict encoding detection when input is bytes.- Large text nodes with lxml: when using an lxml builder and documents may contain a single text node > 10,000,000 bytes, pass
huge_tree=True to BeautifulSoup(...) to avoid lxml security limits truncating the parse.
- Multi-valued attributes:
- Default (HTML):
class/rel etc. become lists.
- To disable list conversion:
BeautifulSoup(markup, "html.parser", multi_valued_attributes=None)
- In XML mode, multi-valued attributes are not enabled by default; you can opt in via
multi_valued_attributes={'*': 'class'}.
Pitfalls
Wrong: Not specifying a parser (inconsistent trees)
from bs4 import BeautifulSoup
html_doc = "<p><b>badly nested</p></b>"
soup = BeautifulSoup(html_doc)
print(soup.find("b"))
Right: Choose a parser explicitly
from bs4 import BeautifulSoup
html_doc = "<p><b>badly nested</p></b>"
soup = BeautifulSoup(html_doc, "html.parser")
print(soup.find("b"))
Wrong: Treating class as a string in HTML mode
from bs4 import BeautifulSoup
soup = BeautifulSoup("<p class='body strikeout'></p>", "html.parser")
classes = soup.p["class"].split()
print(classes)
Right: Use the list directly (or normalize with get_attribute_list)
from bs4 import BeautifulSoup
soup = BeautifulSoup("<p class='body strikeout'></p>", "html.parser")
classes = soup.p["class"]
print(classes)
ids = soup.p.get_attribute_list("id")
print(ids)
Wrong: Assuming multi-valued attributes exist in XML mode
from bs4 import BeautifulSoup
soup = BeautifulSoup("<p class='body strikeout'></p>", "xml")
first = soup.p["class"][0]
print(first)
Right: Opt in to multi-valued attributes when parsing XML
from bs4 import BeautifulSoup
class_is_multi = {"*": "class"}
soup = BeautifulSoup("<p class='body strikeout'></p>", "xml", multi_valued_attributes=class_is_multi)
first = soup.p["class"][0]
print(first)
Wrong: Editing a NavigableString “in place”
from bs4 import BeautifulSoup
from bs4.element import NavigableString
soup = BeautifulSoup("<p>Hello</p>", "html.parser")
text = soup.p.string
assert isinstance(text, NavigableString)
text = NavigableString("Hi")
print(soup.p.get_text())
Right: Replace the existing node with replace_with
from bs4 import BeautifulSoup
from bs4.element import NavigableString
soup = BeautifulSoup("<p>Hello</p>", "html.parser")
text = soup.p.string
assert isinstance(text, NavigableString)
text.replace_with("Hi")
print(soup.p.get_text())
Wrong: lxml builder truncation with huge text nodes (missing huge_tree=True)
from bs4 import BeautifulSoup
markup_with_huge_text = "<root>" + ("x" * 11_000_000) + "</root>"
soup = BeautifulSoup(markup_with_huge_text, "lxml")
print(soup.find("root") is not None)
Right: Enable huge tree support when needed
from bs4 import BeautifulSoup
markup_with_huge_text = "<root>" + ("x" * 11_000_000) + "</root>"
soup = BeautifulSoup(markup_with_huge_text, "lxml", huge_tree=True)
print(soup.find("root") is not None)
References
Migration from v4.13.x
- Typing changes (4.14.0+):
find_* methods gained overloads to improve type safety.
- Prefer annotating results as
Optional[Tag], Optional[NavigableString], Sequence[Tag], etc.
- Known edge case:
find_all("a", string="...") may still confuse type checkers; refactor or use typing.cast.
from __future__ import annotations
from typing import Optional, Sequence, cast
from bs4 import BeautifulSoup, Tag
soup = BeautifulSoup("<a>b</a>", "html.parser")
a: Optional[Tag] = soup.find("a")
tags = cast(Sequence[Tag], soup.find_all("a", string="b"))
print([t.get_text() for t in tags])
-
ResultSet typing churn across 4.14.x: inheritance changed in 4.14.0/4.14.1/4.14.2; avoid depending on specific ABC inheritance.
- If you need a stable container type at boundaries:
results = list(soup.find_all(...)).
-
lxml huge text nodes (4.14.3 note): if using an lxml builder and expecting extremely large text nodes, pass huge_tree=True.
API Reference
- BeautifulSoup(markup, features=..., parse_only=..., from_encoding=..., exclude_encodings=..., element_classes=..., **kwargs) - parse markup into a tree; specify
features (parser) explicitly.
- BeautifulSoup.find(...) - return the first matching element (often
Tag | None); supports tag name, attrs, and other filters.
- BeautifulSoup.find_all(...) - return all matching elements (list-like result set); convert to
list(...) if you need a stable container type.
- BeautifulSoup.find_next(...) / find_all_next(...) - search forward in document order from a starting node.
- BeautifulSoup.find_previous(...) / find_all_previous(...) - search backward in document order from a starting node.
- BeautifulSoup.find_next_sibling(...) / find_next_siblings(...) - search among following siblings.
- BeautifulSoup.find_previous_sibling(...) / find_previous_siblings(...) - search among preceding siblings.
- BeautifulSoup.find_parent(...) / find_parents(...) - search upward to parents/ancestors.
- BeautifulSoup.get_text(separator="...", strip=False) - extract combined text content from a subtree.
- BeautifulSoup.prettify() - render formatted markup for debugging/inspection.
- BeautifulSoup.contains_replacement_characters - flag indicating replacement characters were introduced during entity/encoding handling (builder-dependent).
- Tag.name - the tag’s name (e.g.,
"a", "p").
- Tag.attrs - dict of attributes; multi-valued HTML attributes may be lists.
- Tag.get(key, default=None) - safe attribute lookup.
- Tag.get_attribute_list(name) - normalize an attribute to a list regardless of internal storage.
- UnicodeDammit(...) - helper for detecting/decoding unknown encodings before parsing.
- Comment - class for HTML/XML comment nodes (a specialized string-like node).
- ParserRejectedMarkup - exception raised when the underlying parser rejects markup.
- FeatureNotFound - exception raised when the requested parser feature/builder is unavailable.
