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A toolkit for working with CDX indices

Project description


Build Status Coverage Apache License 2.0

cdx_toolkit is a set of tools for working with CDX indices of web crawls and archives, including those at CommonCrawl and the Internet Archive's Wayback Machine.

CommonCrawl uses Ilya Kreymer's pywb to serve the CDX API, which is somewhat different from the Internet Archive's CDX API server. cdx_toolkit hides these differences as best it can. cdx_toolkit also knits together the monthly Common Crawl CDX indices into a single, virtual index.

Finally, cdx_toolkit allows extracting archived pages from CC and IA into WARC files. If you're looking to create subsets of CC or IA data and then process them into WET or WAT files, this is a feature you'll find useful.


cdx toolkit requires Python 3.

$ pip install cdx_toolkit

or clone this repo and use python ./ install.

Command-line tools

$ cdxt --cc size '*'
$ cdxt --cc --limit 10 iter '*'
$ cdxt --cc --limit 10 --filter '=status:200' iter '*'
$ cdxt --ia --limit 10 iter '*'
$ cdxt --ia --limit 10 warc '*'

cdxt takes a large number of command line switches, controlling the time period and all other CDX query options. cdxt can generate WARC, jsonl, and csv outputs.

** Note that by default, cdxt --cc will iterate over the previous year of captures. **


$ cdxt --help
$ cdxt iter --help
$ cdxt warc --help

for full details. Note that argument order really matters; each switch is valid only either before or after the {iter,warc,size} command.

Add -v (or -vv) to see what's going on under the hood.

Programming example

import cdx_toolkit

cdx = cdx_toolkit.CDXFetcher(source='cc')
url = '*'

print(url, 'size estimate', cdx.get_size_estimate(url))

for obj in cdx.iter(url, limit=1):

at the moment will print:* size estimate 36000
{'urlkey': 'org,commoncrawl)/', 'timestamp': '20180219112308', 'mime-detected': 'text/html', 'url': '', 'status': '200', 'filename': 'crawl-data/CC-MAIN-2018-09/segments/1518891812584.40/warc/CC-MAIN-20180219111908-20180219131908-00494.warc.gz', 'mime': 'text/html', 'length': '5365', 'digest': 'FM7M2JDBADOQIHKCSFKVTAML4FL2HPHT', 'offset': '81614902'}

You can also fetch the content of the web capture as bytes:


There's a full example of iterating and selecting a subset of captures to write into an extracted WARC file in examples/

Filter syntax

Filters can be used to limit captures to a subset of the results.

Any field name listed in cdxt iter --all-fields can be used in a filter. These field names are appropriately renamed if the source is 'ia'. The different syntax of filter modifiers for 'ia' and 'cc' is not fully abstracted away by cdx_toolkit.

The basic syntax of a filter is [modifier]field:expression, for example =status:200 or !=status:200.

'cc'-style filters (pywb) come in six flavors: substring match, exact string, full-match regex, and their inversions. These are indicated by a modifier of nothing, '=', '~', '!', '!=', and '!~', respectively.

'ia'-style filters (Wayback/OpenWayback) come in two flavors, a full-match regex and an inverted full-match regex: 'status:200' and '!status:200'

Multiple filters will be combined with AND. For example, to limit captures to those which do not have status 200 and do not have status 404,

$ cdxt --cc --filter '!=status:200' --filter '!=status:404' iter ...

Note that filters that discard large numbers of captures put a high load on the CDX server -- for example, a filter that returns just a few captures from a domain that has tens of millions of captures is likely to run very slowly and annoy the owner of the CDX server.

See (pywb) and (wayback) for full details of filter modifiers.

CDX Jargon, Field Names, and such

cdx_toolkit supports all (ok, most!) of the options and fields discussed in the CDX API documentation:

A capture is a single crawled url, be it a copy of a webpage, a redirect to another page, an error such as 404 (page not found), or a revisit record (page identical to a previous capture.)

The url used by cdx_tools can be wildcarded in two ways. One way is *, which in CDX jargon sets matchType='domain', and will return captures for,, etc. The other,*, will return captures for any page on

A timestamp represents year-month-day-time as a string of digits run togther. Example: January 5, 2016 at 12:34:56 UTC is 20160105123456. These timestamps are a field in the index, and are also used to pick specify the dates used by --from=, --to, and --closest on the command-line. (Programmatically, use from_ts=, to=, and closest=.)

An urlkey is a SURT, which is a munged-up url suitable for deduplication and sorting. This sort order is how CDX indices efficiently support queries like * The SURTs for and are identical, which is handy when these 2 hosts actually have identical web content. The original url should be present in all records, if you want to know exactly what it is.

The limit argument limits how many captures will be returned. To help users not shoot themselves in the foot, a limit of 1,000 is applied to --get and .get() calls.

A filter allows a user to select a subset of CDX records, reducing network traffic between the CDX API server and the user. For example, filter='!status:200' will only show captures whose http status is not 200. Multiple filters can be specified as a list (in the api) and on the command line (by specifying --filter more than once). Filters and limit work together, with the limit applying to the count of captures after the filter is applied. Note that revisit records have a status of '-', not 200.

CDX API servers support a paged interface for efficient access to large sets of URLs. cdx_toolkit iterators always use the paged interface. cdx_toolkit is also polite to CDX servers by being single-threaded and serial. If it's not fast enough for you, consider downloading Common Crawl's index files directly.

A digest is a sha1 checksum of the contents of a capture. The purpose of a digest is to be able to easily figure out if 2 captures have identical content.

Common Crawl publishes a new index each month. cdx_toolkit will start using new ones as soon as they are published. By default, cdx_toolkit will use the most recent 12 months of Common Crawl; you can change that using --from or from_ts= and --to or to=.

CDX implementations do not efficiently support reversed sort orders, so cdx_toolkit results will be ordered by ascending SURT and by ascending timestamp. However, since CC has an individual index for each month, and because most users want more recent results, cdx_toolkit defaults to querying CC's CDX indices in decreasing month order, but each month's result will be in ascending SURT and ascending timestamp. This default sort order is named 'mixed'. If you'd like pure ascending, set --cc-sort or cc_sort= to 'ascending'. You may want to also specify --from or from_ts= to set a starting timestamp.

The main problem with this ascending sort order is that it's a pain to get the most recent N captures: --limit and limit= will return the oldest N captures. With the 'mixed' ordering, a large enough limit= will get close to returning the most recent N captures.


Content downloading needs help with charset issues, preferably figuring out the charset using an algorithm similar to browsers.

WARC generation should do smart(er) things with revisit records.

Right now the CC code selects which monthly CC indices to use based solely on date ranges. It would be nice to have an alternative so that a client could iterate against the most recent N CC indices, and also have the default one-year lookback use an entire monthly index instead of a partial one.


cdx_toolkit has reached the beta-testing stage of development.


Copyright 2018-2020 Greg Lindahl and others

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this software except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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