Downloading test builds
From Second Life Wiki
Many developers, both inside Linden Lab and in Open Source, are constantly implementing new features and fixing problems with the viewer. One of the most important ways that you can help with that process as a user is to install and try these development viewers and provide feedback.
All of the viewers here are under active development - there may be some problems with existing features; if you want a more stable experience, use the released Second Life Viewer.
There are several places to look for viewers that need testing:
Various viewer development projects working on major new features may from time to time release Project Viewers to provide early testing opportunities. You can find any that are currently available on the Alternate Viewers page.
Other Snowstorm Team Builds
Tracking of Snowstorm issues can be seen on the Snowstorm dashboard in Jira.
Everyone may post links here to viewers that should be tested, provided the viewers are Second Life compatible and TPVp compliant when connected to Second Life.
Development Mailing List
Developers who are looking for testers sometimes make requests for testing on the opensource-dev mailing list.