The Alliance has compiled this set of website accessibility resources from throughout the nonprofit and museum sector.
The Association of Research Libraries (ARL) has developed a number of resources to help organizations develop more accessible websites.
This website provides information from the University of Washington about building accessible websites on a more detailed level for content.
This checklist from Vox Media can help build accessibility into the website development process and include items like using contrast, utilizing color effectively, use of images, understanding inputs, alt text, and consistency and clarity.
Information on WCAG, the Web Content Accessibility Guidelines. A single shared standard for web content accessibility that meets the needs of individuals, organizations, and governments internationally.
WebAIM offers this set of resources to help achieve technical accessibility on your website from the users perspective.
The World Wide Web Consortium (W3C) has a Web Accessibility Initiative and numerous resources. They provide guidelines, quick tips, checklists, techniques, and training materials for making web content accessible. They also have descriptions of and links to more than 30 tools that can help with evaluation, retrofitting, and transformation of Web content. In addition, they offer guidance in developing organizational policies on Web accessibility and selecting authoring tools for Web accessibility.