Company
Mega-Index
Federated Search
Discovery Layer (suitable for articles)
Notes
EBSCO
EBSCO Discovery Service
Integrated Search
Discovery Service?

Ex Libris
Primo Central Index
MetaLib
Primo

Serials Solutions
Summon
360 Search
AquaBrowser

III

Research Pro
Encore (just for books, not articles?)

open source


VuFind, Xerxes, Blacklight