Moodle complies with the Web Content Accessibility Guidelines (WCAG) 2.1 AA conformity for accessibility. This means that the programming already supports the accessible design of courses. Even more important is however the implementation of the content by teachers and course leaders.
Moodle contains (since version 3.11) the Brickfield Accessibility Starter Toolkit. Teachers can use this analysis function on request and receive tips on how to optimize their own course.

• Start analysis: Course page > Actions menu > “More” > “Accessibility Toolkit”.
• Accessibility Toolkit on Moodle.org.

More information on how to avoid or keep barriers low within a Moodle course:

• Moodle-Kursgestaltung und Barrierefreiheit (Poster with hints for barrier-free design, PDF in German)

• Accessibility on Moodle.org

• Humboldt University Berlin: Information and examples: Barrier-free Moodle (via guest login)

• University of Düsburg (UDE): Design of accessible Moodle course rooms (can be used via guest login)