Please see the vendor statements linked here regarding compliance with WCAG 2.1, Level AA standards:

Vendor Titles Accessibility Statements and Reports
BiblioLabs
American and English full text literature collections
 BiblioLabs Accessibility Conformance Report
EBSCO
Biography Reference Bank
Business Source Premier
Consumer Health Complete
EBSCOhost
Explora for Middle Schools
Explora Primary Schools
Explora Primary Schools
Hobbies and Crafts Source
Home Improvement Source
Literary Reference Source
Points of View Reference Source
Science Reference Source
Small Business Source

EBSCO Platform Accessibility Statement

 
Gale
Chilton Library
 Gale Platform Accessibility Statement
Northstar
Northstar Digital Literacy
 Northstar Digital Literacy Accessibility Statement
Oxford University Press
Oxford Research Encyclopedias
Very Short Introductions
 Oxford Academic Platform Accessibility Statement
ProQuest
African American Heritage
Ancestry Library Edition
CultureGrams
Fold3
HeritageQuest

African American Heritage Conformance Report

Ancestry Library Edition Accessibility Statement

CultureGrams Accessibility Statement

Fold3 Accessibility Statement

Heritage Quest Online Accessibility Statement
World Book
World Book - Banco de Contenidos aulaPlaneta
World Book - Enciclopedia Estudiantil Hallazgos
World Book - L'Encyclopédie Découverte
World Book Advanced
World Book Advanced
World Book Kids
World Book Student
World Book Timelines
 World Book Online VPATs