I haven’t seen a thread related to iOS TestFlight beta opportunities, so thought I would post a few links that I’ve come across. Feel free to edit this post with your own discoveries, or post below and I’ll be more than happy to update.
Note: Some beta programs may be full, but change on a daily basis so please keep checking back if your requested beta is full.
Google Chrome https://bit.ly/2RGoAJi
Microsoft Cortana https://testflight.apple.com/join/4IHpEYnz
Microsoft Excel https://testflight.apple.com/join/3lIiz1eZ
Microsoft OneDrive https://testflight.apple.com/join/LtgPLzrQ
Microsoft OneNote https://testflight.apple.com/join/uDgoqfGS
Microsoft Outlook https://testflight.apple.com/join/QkU4VS1s
Microsoft PowerPoint https://testflight.apple.com/join/a9Ef0N3g
Microsoft To-Do https://testflight.apple.com/join/JSq3UkAz
Microsoft Word https://testflight.apple.com/join/hw76phYi
Mozilla Firefox https://mzl.la/2CecUU7
Skype (for iPhone) https://testflight.apple.com/join/fB5IkJT7
Skype (for iPad) https://testflight.apple.com/join/vnSIsolv