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From Wikitech

X-Analytics is an HTTP header used for measurement purposes, including in cache log format and the webrequest data stream.

Generally, values are added to the header on the server side; the only keys accepted from the client side are preview and pageview.


The X-Analytics header is formatted as a list of key=value pairs separated by semicolons, like mf-m=b or zero=123-45;mf-m=b. If a key occurs more than once, it is undefined which one takes precedence.

The special value - must be interpreted as the empty string.


Looks like X-Analytics extension might be adding these values if used: [1]

Key Value Origin Since Until Team Contact Use case
mf-m b, amc, b,amc, or not set appserver ? Current Readers Web Phuedx If set, then the value b indicates that the user is opted into the beta mode (of the mobile site) (mf-m=b), the value amc indicates Advanced Mobile Contributions (mf-m=amc), and b,amc indicates both (mf-m=b,amc). See MobileContext.php.
proxy Proxy name, e.g. Opera varnish ? Current Wikipedia Zero Yurik If set, indicates that this request has been received via one of the trusted proxies such as Opera Mini servers.

Currently, the following proxies can be expected:

Value Description
Opera Opera mini proxy
Nokiaprod Nokia Xpress Production Proxy Servers
Nokiaqa Nokia Xpress QA Lab Proxy Servers
IORG Internet.org (set by analytics.inc.vcl in puppet)
https 1 varnish ? Current SRE Traffic BBlack If set, will be equal to "1", indicating HTTPS protocol. Currently set for the vast majority of requests, including all that are served with content from canonical WMF domains. If it is missing and the HTTP status is 301, the request was sent using HTTP and met with a HTTP redirect response, most likely to the corresponding HTTPS URL. For other response codes <400 (non-errors), it is assumed that the absence of this field also indicates a HTTP request. For some rare cases involving response codes >= 400, it may be possible that this field is not set even though the request was over HTTPS. (More details)
wmfuuid UUID v4 value varnish ? Current Mobile apps dr0ptp4kt If set, will be equal to a hyphen separated value, and indicates a unique app installation. The ID may span multiple requests, as it is generated once, at app install time, using an appropriate library (Java, Objective C), and conforms to RFC 4122 version 4.

Older versions of the app may contain an appInstallID parameter in the request URL instead, or may contain both the appInstallID parameter in the URL as well as the wmfuuid X-Analytics value. Later versions of the software should only contain the wmfuuid X-Analytics value and not the appInstallID parameter in the URL.

Requests from the app will not contain this header if the user has turned off "Send usage reports" in the settings menu of the app.

WMF-Last-Access dd-MMM-yyyy, e.g. 06-May-2015 varnish ? Current Analytics (Infrastructure) Milimetric Date of site last access. If set will be equal to the latest date when a device issued a request to the specific host in dd-MMM-yyyy format(Eg: 06-May-2015) and an expiration date set to ~31 days in the future. More explanation at Analytics/Unique_clients/Last_access_solution.
preview 1 client ? Analytics (Infrastructure) Milimetric Whether this is a preview request (not present if not). At the time of this writing, preview requests by mobile apps are not consider pageviews.

Expected value is preview=1.

Not actively used as of Dec 2021 (task T297172#7567161).

pageview 1 client ? Current Analytics (Infrastructure) Milimetric If set it will count the request in question as a pageview regardless of other attributes of request.
nocookies 1 varnish ? Current Analytics (Infrastructure) Madhuvishy or Nuria If set it will tag the request in question as a nocookie request. This means that either this is a fresh browser session, a user browsing with cookies disabled or possibly a bot request.

We expect that the majority of requests tagged with nocookies will belong to bots. Please see: change 244626.

loggedIn 1 appserver (WikimediaEvents) ? WMDE-Analytics Addshore If set, will be equal to "1", and indicates that the request came from a logged in user (see also code).
page_id Page ID appserver (WikimediaEvents) ? WMDE-Analytics Addshore, Ori.livneh If set, will be a string of a positive integer.
ns Namespace ID appserver (WikimediaEvents) ? WMDE-Analytics Addshore, Ori.livneh If set, will be a string integer (can be negative for negative namespace IDs)
special Special page name appserver (WikimediaEvents) ? WMDE-Analytics Addshore Set for special pages only. This will be the base name of the special page, so if the user is browsing a page via an alias the actual page name will be here.
translationengine Identifier, e.g. GT varnish Nov 2018 Current Product ABaso If set, indicates request served through a known intermediary service for machine translations. "GT" stands for Google Translate.

Added in T208795.

wprov <3_char_feature>


e.g. srpw1 for SRP, Web, v1.

client or varnish ? Current ? ? see Provenance
debug 1 varnish Jan 2021 Current Analytics (Infrastructure) Milimetric Added in T263683.
client_port medium-size int varnish Jan 2021 Current Analytics (Infrastructure) JAllemandou Added in T271953.
public_cloud 1 varnish May 2021 Current SRE CDanis Added in T279380.
sessioncookie 1 varnish November 2022 Current SRE Vgutierrez Added in T319324.
prefetch_sec_purpose chrome_private_prefetch, chrome_prerender, chrome_preview, 1, or nonstandard varnish January 2024 Current Analytics (Infrastructure) ABaso / AOtto Added in T346463.
chrome_private_prefetch_version 1, or later on an incremented version varnish January 2024 Current Analytics (Infrastructure) ABaso / AOtto Added in T346463.
prefetch_purpose 1 varnish January 2024 Current Analytics (Infrastructure) ABaso / AOtto Added in T346463. Note that this may be present in conjunction with other prefetch tagged values.
prefetch_x_moz 1 varnish January 2024 Current Analytics (Infrastructure) ABaso / AOtto Added in T346463.
rev_id Revision ID appserver (WikimediaEvents) February 2024 Current ? ? Added in T346350.

Former keys

Key Value Origin Since Until Team Contact Use case
php zend, or hhvm appserver ? Jan 2015 SRE _joe_ If set, marks the used PHP implementation.

This tag was only set between September 2014 and January 2015 during the migration from Zend to HHVM. (See I46ff99, and I75b30b)

zero MCC-MNC of a zero carrier, e.g. 404‑01. varnish ? July 2019 Wikipedia Zero Yurik If set, indicates that this request has been associated with the given carrier. It does not mean that the request qualifies as page view.

Removal in T213769.

zeronet Subdivision of a carrier, e.g. b varnish ? July 2019 Wikipedia Zero Yurik Used of disambiguate between different parts/configurations of a single carrier. Like broadband vs. special access points.

Removal in T213769.

max-snippet 1, 0, or not set appserver (WikimediaEvents) Mar 2022 Current Readers Web cjming If set, the value 1 indicates the page's robots meta tag contains the max-snippet directive. The value 0 indicates the page's robots meta tag does not contain the max-snippet directive. If set, both 1 and 0 indicate that the page is part of an A/B test in the treatment and control groups respectively. Added in T301584.

Removed in I65ce99b04acc as part of T310267.



Extension documentation


Tasks and Bugs


See also