Viral Loops - Viral Loops is a viral and referral marketing platform to launch ranking competitions, sweepstakes, pre-launch and referral programs.

Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.

Referral Candy - Run a fully automated, customizable and easy to integrate referral program for ecommerce.

Influitive - Influitive helps companies increase customer lifetime value and accelerate sales with the power of their own customer advocates. Inspire your customers to stay longer, share their experiences, and attract new business.

InviteBox - Acquire new customers with a social referral program. InviteBox is a flexible referral marketing solution that brings you new customers at no cost.

Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.