IGdm - Instagram direct messaging on your laptop
Evite - Send online invitations for all occasions by email or text message. Create invites for birthdays, baby showers, save the dates, or customize your own design.
PlanItUp - The easiest and fastest way to make plans with your friends
RSVPify - A powerful and awesomely customizable platform for selling tickets online for your event.
Turnout - Make plans with text-based RSVPs
JustRSVP.me - Online Invitations and response tracking for weddings, baby showers, birthdays, parties, and other...