Citations of online sources that require registration or a subscription are acceptable in Wikipedia as documented in Verifiability § Access to sources. As a courtesy to readers and other editors, editors should signal restrictions on access to material provided via the external links included in a citation. These levels describe requirements or constraints related to accessing and viewing the cited material; they are not intended to indicate the ability to reuse, or the copyright status, of the material, since that status is not relevant to verifying claims in articles.

Four access levels can be used:

  • access indicator for named identifiers:
    • Freely accessible free: the source is free to read for anyone
  • access indicators for url-holding parameters:
    • Free registration required registration: a free registration with the provider is required to access the source, even if a limited preview, abstract or review may still be available without registration
    • Free access subject to limited trial, subscription normally required limited: free access is subject to limited trial and a subscription is normally required
    • Paid subscription required subscription: the source is only accessible via a paid subscription with the provider of the source ("paywall")

As there are often multiple external links with different access levels in the same citation, each value is attributed to a specific external link.

Access indicators for url-holding parameters
සංස්කරණය

Online sources linked by |url=, |article-url=, |chapter-url=, |contribution-url=, |entry-url=, |map-url=, and |section-url= are presumed to be free-to-read. When they are not free-to-read, editors should mark those sources with the matching access-indicator parameter so that an appropriate icon is included in the rendered citation. Because the sources linked by these url-holding parameters are presumed to be free-to-read, they may not be marked as free.

URL-holding and access-indicator parameters
URL Access Allowed keywords
|url= |url-access= registration Free registration required
limited Free access subject to limited trial, subscription normally required
subscription Paid subscription required
|article-url= |article-url-access=
|chapter-url= |chapter-url-access=
|contribution-url= |contribution-url-access=
|entry-url= |entry-url-access=
|map-url= |map-url-access=
|section-url= |section-url-access=

For example, this cites a web page that requires registration but not subscription:

{{cite web |url=https://example.com/nifty_data.php |url-access=registration |date=2021-04-15 |title=Nifty example data}}

which renders as:

"Nifty example data". 2021-04-15. https://example.com/nifty_data.php. 
Access indicator for named identifiers
සංස්කරණය

Links inserted by named identifiers are presumed to lie behind a paywall or registration barrier – exceptions listed below. When they are free-to-read, editors should mark those sources with the matching access-indicator parameter so that an appropriate icon is included in the rendered citation. When the sources linked by these named-identifier parameters are not presumed to carry a free-to-read full text (for instance because they're just abstracting services), they may not be marked as limited, registration, or subscription.

Named-identifier and access-indicator parameters
Identifier Access Allowed keywords
|bibcode= |bibcode-access= free Freely accessible
|doi= |doi-access=
|hdl= |hdl-access=
|jstor= |jstor-access=
|ol= |ol-access=
|osti= |osti-access=
|s2cid= |s2cid-access=

Some named-identifiers are always free-to-read. For those named identifiers there are no access-indicator parameters; the access level is automatically indicated by the template. These named identifiers are:

  • |arxiv=
  • |biorxiv=
  • |citeseerx=
  • |pmc=
  • |rfc=
  • |ssrn=

For embargoed pmc that will become available in the future, see pmc-embargo-date.