Alternatively, consider adding a tag to the edit summary if a Web2Cit-generated citation was inserted. This seems to be what Proveit does.

We would need community approval, as the tag should be added to each Wikipedia's Special:Tags.

Also @Sophivorus recommended maybe using mw.track() as used in ProveIt gadget.

See here for an example of the kind of charts produced via mw.track

We would need community approval, as the tag should be added to each Wikipedia's Special:Tags.

There're two kinds of "tags": change tags and hash tags. Change tags need to be approved by each Wikipedia and defined in Special:Tags before they can be set for any edit. However, hashtags are simply strings like #Web2Cit that you can add to an edit summary (either manually or programmatically), and can then be tracked via https://hashtags.wmcloud.org. They do not need any previous approval from each wiki and are therefore far more convenient.

Furthermore, I'd recommend adding [[meta:Web2Cit|#Web2Cit]] rather than just #Web2Cit, to add some extra context by linking back to your main documentation page, and also to do some "advertising" for your tool. However, if you do, the https://hashtags.wmcloud.org tool will not detect the hashtag, UNLESS YOU ADD A SPACE BEFORE THE HASH, like so: [[meta:Web2Cit| #Web2Cit]]

Gracias @Sophivorus! That's all very useful information.

We may thus consider further tweaking the Citoid extension to add something (maybe a comment?) to the citation template if it was inserted using Web2Cit-generated data.

The good thing of this approach is that we can more reliably confirm that Web2Cit was used to introduce a citation, and which citation that was. The edit summary alternative approach may be less reliable, as users may add a citation with Web2Cit, but then decide to remove the citation before publishing the changes.

On the other hand, I see at least two problems with this approach. First, that it will have to be internationalized to fit different language Wikipedias, if we want to include a comment more explanatory than simply "Web2Cit". Second, that the comment would probably remain in place even if the citation is edited in later revisions (although it would continue to be true that it was originally added with Web2Cit).

The Cite news template documentation, for example, shows an example of how comments may be used inside citation templates. In our case it could be something like: {{Cite news<!--Inserted with Web2Cit-->|author=...}}.

First, that it will have to be internationalized to fit different language Wikipedias, if we want to include a comment more explanatory than simply "Web2Cit".

We may workaround this by using messages from other components, such as Citoid extension's citoid-citoiddialog-credit (Powered by $1).

the Wikipedia community may reasonably not like them, as it would add some clutter to Wikipedia articles.

These are English Wikipedia recommendations about using this kind of invisible comments:

• https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style/Hidden_text
• https://en.wikipedia.org/wiki/Help:Wikitext#Invisible_text_(comments)
• https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style#Invisible_comments

Our proposed use case is not listed but doesn't seem to be explicitly forbidden either, although they say its use should not be abused.