Why Do Documents Download Instead of Opening in the Browser?

Accessibility

Opening anything in a new browser window without letting users know is a violation of the Web Content Accessibility Guidelines (WCAG). 

Downloaded PDFs can be made more accessible for people who rely on assistive technologies, such as text-to-speech and screen reader compatibility.

User Experience 

Through working closely with government agencies, we’ve observed that PDFs are commonly used as their own content. While creating the content on a webpage delivers the most optimal user experience, some agencies are legally required to provide the information in PDF format.

In these cases, users have more options when downloading a PDF to their computer. They are able to utilize certain features in their PDF reader that cannot be done in a browser window, such as viewing the PDF offline and adding annotations.