ShortStack - Shortstack is a website that allows you to create viral online events for your social media followers or other online audience.
ViralSweep - Grow your fans and increase sales with sweepstakes and giveaways.
HubSpot Marketing Hub - HubSpot is a cloud-based inbound marketing software that allows businesses to transform the way that they market online.
Heyo - Use Heyo to easily create Sweepstakes, Contests, and Campaign apps that publish to Mobile, Facebook, and anywhere on the web.
Woobox - Woobox helps you easily create powerful contests, sweepstakes, coupons, and more to grow your fans...
UpViral - Referral marketing platform enables anyone in running effective and profitable viral marketing campaigns – in minutes.