Airsketch - Simple screenshots + annotations for Mac 🖥️
Basil Chat - Design feedback via chat
FakeClients Feedback - 🖌 A simple, free to use platform for design feedback
Planogy - A feedback platform for all the creative work
Slack E-mail Add-ins - Quickly forward emails and attachments to Slack
Feedback by Pixelic - Painless design feedback and version control.