The case against Google that the European Commission has filed is said to be based on 19 complainants.

Google's upcoming battle with the European Commission is reportedly based upon 19 complainants, according to Re/code. We first learned of the groundwork being laid out for the case in the beginning of April, and mid-month the EU formally filed the charges.

The European Union's decision to take on Google last week stems from official complaints by 19 companies in Europe and the United States, including Microsoft and a number of small firms, people familiar with the matter said on Friday.
The benefit of being an official complainant in the case is that it gives the companies additional access to the regulatory proceedings. They will be able to get a detailed copy of the EU charge sheet as well as argue their case at a hearing of competition experts.

Some of the big name companies that are rumored to be listed as complainants in the case include eJustice, Yelp, Expedia, TripAdvisor, and even Microsoft.

The next few months will be interesting, as we see additional details from the case continue to surface.