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May 2, 2018

April 2018 Crawl Archive Now Available

The crawl archive for April 2018 is now available! The archive contains 3.1 billion web pages and 230 TiB of uncompressed content, crawled between April 19th and 27th.

The crawl archive for April 2018 is now available! The archive is located in the commoncrawl bucket at crawl-data/CC-MAIN-2018-17/. It contains 3.1 billion web pages and 230 TiB of uncompressed content, crawled between April 19th and 27th.

Data Type File List #Files Total Size
Compressed (TiB)
Segments segment.paths.gz 100
WARC warc.paths.gz 64320 54.24
WAT wat.paths.gz 64320 19.22
WET wet.paths.gz 64320 8.40
Robots.txt files robotstxt.paths.gz 64320 0.20
Non-200 responses non200responses.paths.gz 64320 1.58
URL index files cc-index.paths.gz 302 0.23
Columnar URL index files cc-index-table.paths.gz 900 0.26

The April crawl contains 625 million new URLs, not contained in any crawl archive before. New URLs are “mined” by

  • extracting and sampling URLs from
  • sitemaps if provided by any of the highest-ranking 100 million hosts taken from the Nov/Dec/Jan 2017/2018 webgraph data set
  • RSS and Atom feeds (random sample of 1 million feeds taken from the March crawl data)
  • a breadth-first side crawl within a maximum of 4 links (“hops”) away from the home pages of the top 40 million hosts or top 40 million domains of the webgraph dataset
  • a random sample taken from WAT files of the March crawl

We took actions to reduce the amount of images unintentionally crawled: Although our crawler is focused to fetch HTML pages, there has always been a small amount (1-2%) of other document formats. We accept these – it's a part of the web and these WARC records are useful to gain insights, e.g. to test PDF or Office document parsers at scale.

However, because image links contained in sitemaps haven't properly filtered out, the amount of images has grown during the last time and reached 2% in March 2018.

As a result of filtering image links from sitemaps, the amount of images now has dropped to approx. 0.5%, cf. the MIME type statistics of the latest three monthly crawls.

To assist with exploring and using the dataset, we provide gzipped files which list all segments, WARC, WAT and WET files.

By simply adding either s3://commoncrawl/ or https://data.commoncrawl.org/ to each line, you end up with the S3 and HTTP paths respectively.

The Common Crawl URL Index for this crawl is available at: https://index.commoncrawl.org/CC-MAIN-2018-17/. Also the columnar index has been updated to contain this crawl.

Please donate to Common Crawl if you appreciate our free datasets! We’re also seeking corporate sponsors to partner with Common Crawl for our non-profit work in open data. Please contact info@commoncrawl.org for sponsorship information.

This release was authored by:
No items found.

Erratum: 

WARC Content-Type header in revisit records

Originally reported by: 
Sebastian Nagel
More details
Common Crawl's WARC revisit records use Content-Type: message/http (following the WARC 1.1 spec's example), but per iipc/warc-specifications#55 it should be application/http;msgtype=response for consistency with other HTTP response records.

Erratum: 

WARC-Target-URI May Include Non-ASCII Characters

Originally reported by: 
More details
The WARC-Target-URI header in WARC record, but also corresponding WAT, WET and URL index records may include non-ASCII characters, not encoded using percent-encoding or Punycode.

Erratum: 

Content is truncated

Originally reported by: 
More details
Some archived content is truncated due to fetch size limits imposed during crawling. This is necessary to handle infinite or exceptionally large data streams (e.g., radio streams). Prior to March 2025 (CC-MAIN-2025-13), the truncation threshold was 1 MiB. From the March 2025 crawl onwards, this limit has been increased to 5 MiB.

Erratum: 

No Truncation Indicator in WARC Records

Originally reported by: 
Henry Thompson
More details
Due to an issue with our crawler, not all truncations were indicated correctly. A workaround to detect length truncation is to be suspicious if the length of the content is exactly 1048576 bytes. Truncations for time or network do not have such a workaround. In the WARC files this indicator is called "WARC-Truncated".

Erratum: 

Missing content_truncated flag in URL indexes

Originally reported by: 
More details
The flag in our URL indexes (CDX and columnar) that indicates whether or not a WARC record payload was truncated was added in CC-MAIN-2019-47. This indicator is missing in our indexes for all previous crawl releases. In the CDX index this is referred to as "truncated", and the columnar index refers to this as "content_truncated".

Erratum: 

SURT URLs do not properly encode non-UTF-8 percent-encoded characters

Originally reported by: 
Tom Morris
More details
When constructing SURT (Sort-friendly URI Reordering Transform) URLs, percent-encoded characters that are not valid UTF-8 sequences were not being correctly handled. This could lead to inconsistencies in URL normalization and sorting, potentially causing incorrect deduplication or retrieval issues in datasets that rely on SURT-based indexing.

Erratum: 

WAT data: repeated WARC and HTTP headers are not preserved

Originally reported by: 
More details
Repeated HTTP and WARC headers were not represented in the JSON data in WAT files.

Erratum: 

Erroneous title field in WAT records

Originally reported by: 
Robert Waksmunski
More details
The title field in WAT record is extracted from last but not first <title> element in an HTML page

Erratum: 

Missing Language Classification

Originally reported by: 
More details
Starting with crawl CC-MAIN-2018-39 we added a language classification field (‘content-languages’) to the columnar indexes, WAT files, and WARC metadata for all subsequent crawls.