ViralSweep - Grow your fans and increase sales with sweepstakes and giveaways.
Tagwin - Instagram contests & giveaways made easy
Retweet Picker - Retweet Picker is an online tool that is helping you to select the random winner from Twitter for the giveaways.
Cominsoon - Build coming soon page to get early feedback
KingSumo - Grow your audience with viral giveaways that cut marketing costs
Waitlisted - Waitlisted helps new brands and startups build an audience while they focus on building a product