Quick Statements is a tool originally developed for Wikidata. It is a bit fickle, but can be a great help if you have a spreadsheet you want to "upload" to the wiki.
The tool is available at qs.personaldata.io (select "New Batch").
A user manual is integrated (make sure to use the CSV input syntax, which is a bit easier to use), but otherwise you can rely on the help for Wikidata's implementation of Quick Statements.
In general, you want to use a CSV file. As an example, this will create two instance of (P3) - data controller (Q96), with the proper labels, and e-mail address (P17). This is interpreted as a creation because no qid are given (if qids were given, then the corresponding item would be "updated", but what constitutes an update (rather than creating a new statement) is a bit vague to me).
qid,Len,P3,P17 ,Company 1,Q96,"""mailto:firstname.lastname@example.org""" ,Company 2,Q96,"""mailto:email@example.com"""
Note the absolutely insane syntax: you need to use triple quotes for entering strings properly, but not for labels. That's the world of software for you. Make sure to do some testing before entering dozens of new entries.