With Python#

The Python programming language#

Python can be easy to pick up whether you’re a first time programmer or you’re experienced with other languages:



# load necessary components
>>> from trafilatura import fetch_url, extract

# download a web page
>>> url = 'https://github.blog/2019-03-29-leader-spotlight-erin-spiceland/'
>>> downloaded = fetch_url(url)
>>> downloaded is None  # assuming the download was successful

# extract information from HTML
>>> result = extract(downloaded)
>>> print(result)
# newlines preserved, TXT output ...

The only required argument is the input document (here a downloaded HTML file), the rest is optional.


For a hands-on tutorial see also the Python Notebook Trafilatura Overview.


Default output is set to TXT (bare text) without metadata.

The following formats are available: bare text, text with Markdown formatting, CSV, JSON, XML, and XML following the guidelines of the Text Encoding Initiative (TEI).


Combining TXT, CSV and JSON formats with certain structural elements (e.g. formatting or links) triggers output in TXT+Markdown format.

The variables from the example above can be used further:

# newlines preserved, TXT output
>>> extract(downloaded)

# TXT/Markdown output
>>> extract(downloaded, include_links=True)

# some formatting preserved in basic XML structure
>>> extract(downloaded, output_format='xml')

# source URL provided for inclusion in metadata
>>> extract(downloaded, output_format='xml', url=url)

# links preserved in XML, converting relative links to absolute where possible
>>> extract(downloaded, output_format='xml', include_links=True)

# source URL must be provided to convert relative links to absolute with TXT output
>>> extract(downloaded, include_links=True, url=url)

Choice of HTML elements#

Several elements can be included or discarded:

  • Text elements: comments, tables

  • Structural elements: formatting, images, links

Their inclusion can be activated or deactivated using paramaters passed to the extract() function:

# no comments in output
>>> result = extract(downloaded, include_comments=False)

# skip tables examination
>>> result = extract(downloaded, include_tables=False)

# output with links
>>> result = extract(downloaded, include_links=True)
# and so on...


Including extra elements works best with conversion to XML formats (output_format="xml") or bare_extraction(). Both ways allow for direct display and manipulation of the elements. Certain elements are only visible in the output if the chosen format allows it (e.g. images and XML).


Keep structural elements related to formatting (<b>/<strong>, <i>/<emph> etc.)


Keep link targets (in href="...")


Keep track of images along with their targets (<img> attributes: alt, src, title)


Extract text from HTML <table> elements.

Only include_tables is activated by default.


If the output is buggy removing a constraint (e.g. formatting) can greatly improve the result.

Optimizing for precision and recall#

The parameters favor_precision & favor_recall can be passed to the extract() & bare_extraction() functions:

>>> result = extract(downloaded, url, favor_precision=True)

They slightly affect processing and volume of textual output, respectively concerning precision/accuracy (i.e. more selective extraction, yielding less and more central elements) and recall (i.e. more opportunistic extraction, taking more elements into account).


This function emulates the behavior of similar functions in other packages, it is normally used as a last resort during extraction but can be called specifically in order to output all possible text:

>>> from trafilatura import html2txt
>>> html2txt(downloaded)

Language identification#

The target language can also be set using 2-letter codes (ISO 639-1), there will be no output if the detected language of the result does not match and no such filtering if the identification component has not been installed (see above installation instructions) or if the target language is not available.

>>> result = extract(downloaded, url, target_language="de")


Additional components are required: pip install trafilatura[all]

Optimizing for speed#

Execution speed not only depends on the platform and on supplementary packages (trafilatura[all], htmldate[speed]), but also on the extraction strategy.

The available fallbacks make extraction more precise but also slower. The use of fallback algorithms can also be bypassed in fast mode, which should make extraction about twice as fast:

# skip algorithms used as fallback
>>> result = extract(downloaded, no_fallback=True)

The following combination can lead to shorter processing times:

>>> result = extract(downloaded, include_comments=False, include_tables=False, no_fallback=True)

Content hashing#

Functions used to build content hashes can be found in hashing.py.

# create a filename-safe string by hashing the given content
>>> from trafilatura.hashing import generate_hash_filename
>>> generate_hash_filename("This is a text.")

The SimHash method (also called Charikar’s hash) allows for near-duplicate detection. It implements a locality-sensitive hashing method based on a rolling hash and comparisons using the hamming distance. Overall it is reasonably fast and accurate for web texts and can be used to detect near duplicates by fixing a similarity threshold.

# create a Simhash for near-duplicate detection
>>> from trafilatura.hashing import Simhash
>>> first = Simhash("This is a text.")
>>> second = Simhash("This is a test.")
>>> second.similarity(first)

# use existing Simhash
>>> first_copy = Simhash(existing_hash=first.hash)
>>> first_copy.similarity(first)

Extraction settings#


See also settings page.

Disabling signal#

A timeout exit during extraction can be turned off if malicious data are not an issue or if you run into an error like signal only works in main thread. In this case, the following code can be useful as it explicitly changes the required setting:

>>> from trafilatura.settings import use_config
>>> newconfig = use_config()
>>> newconfig.set("DEFAULT", "EXTRACTION_TIMEOUT", "0")
>>> extract(downloaded, config=newconfig)

Metadata extraction#


Among metadata extraction, dates are handled by an external module: htmldate. By default, focus is on original dates and the extraction replicates the fast/no_fallback option.

Custom parameters can be passed through the extraction function or through the extract_metadata function in trafilatura.metadata, most notably:

  • extensive_search (boolean), to activate further heuristics (higher recall, lower precision)

  • original_date (boolean) to look for the original publication date,

  • outputformat (string), to provide a custom datetime format,

  • max_date (string), to set the latest acceptable date manually (YYYY-MM-DD format).

# import the extract() function, use a previously downloaded document
# pass the new parameters as dict
>>> extract(downloaded, output_format="xml", date_extraction_params={
        "extensive_search": True, "max_date": "2018-07-01"


Even if the page to process has already been downloaded it can still be useful to pass the URL as an argument. See this previous bug for an example:

# define a URL and download the example
>>> url = "https://web.archive.org/web/20210613232513/https://www.thecanary.co/feature/2021/05/19/another-by-election-headache-is-incoming-for-keir-starmer/"
>>> downloaded = fetch_url(url)

# content discarded since necessary metadata couldn't be extracted
>>> bare_extraction(downloaded, with_metadata=True)

# date found in URL, extraction successful
>>> bare_extraction(downloaded, with_metadata=True, url=url)

Memory use#

Trafilatura uses caches to speed up extraction and cleaning processes. This may lead to memory leaks in some cases, particularly in large-scale applications. If that happens you can reset all cached information in order to release RAM:

>>> from trafilatura.meta import reset_caches

# at any given point
>>> reset_caches()

Input/Output types#

Python objects as output#

The extraction can be customized using a series of parameters, for more see the core functions page.

The function bare_extraction can be used to bypass output conversion, it returns Python variables for metadata (dictionary) as well as main text and comments (both LXML objects).

>>> from trafilatura import bare_extraction
>>> bare_extraction(downloaded)

Raw HTTP response objects#

The fetch_url() function can pass a urllib3 response object straight to the extraction by setting the optional decode argument to False.

This can be useful to get the final redirection URL with response.url and then pass is directly as a URL argument to the extraction function:

# necessary components
>>> from trafilatura import fetch_url, bare_extraction
# load an example
>>> response = fetch_url("https://www.example.org", decode=False)
# perform extract() or bare_extraction() on Trafilatura's response object
>>> bare_extraction(response, url=response.url) # here is the redirection URL

LXML objects#

The input can consist of a previously parsed tree (i.e. a lxml.html object), which is then handled seamlessly:

# define document and load it with LXML
>>> from lxml import html
>>> my_doc = """<html><body><article><p>
                Here is the main text.
>>> mytree = html.fromstring(my_doc)
# extract from the already loaded LXML tree
>>> extract(mytree)
'Here is the main text.'