The coverage of different researcher profile sites and their citation statistics varies. Google Scholar seems to be the site with the largest coverage, – it even crawls and indexes my slides. The open Wikidata is far from there, but may be the only one with machine-readable free access and advanced search.
Below is the citation statistics in the form of the h-index from five different services.
|18||Web of Science|
Semantic Scholar does not give an overview of the citation statistics, and the count is somewhat hidden on the individual article pages. I attempted as best as I could to determine the value, but it might be incorrect.
I made a similar statistics on 8 May 2017 and reported it on the slides Wikicite (page 42). During the one and a half month since that count, the statistics for Scopus has change from 20 to 22.
Semantic Scholar is run by the Allen Institute for Artificial Intelligence, a non-profit research institute, so they may be interested in opening up their data for search. An API does, to my knowledge, not (yet?) exist, but they have a gentle robots.txt. It is also possible to download the full Semantic Scholar corpus from http://labs.semanticscholar.org/corpus/. (Thanks to Vladimir Alexiev for bringing my attention to this corpus).