Yes, both OneSignal and NotifyVisitors offer a Free Trial.
OneSignal is designed for Individuals, Freelancers, Large Enterprises, Medium Business and Small Business.
NotifyVisitors is designed for Large Enterprises, Medium Business and Small Business.
The starting price of OneSignal begins at $9/Month, while pricing details for NotifyVisitors are unavailable.
Some top alternatives to OneSignal includes VWO Engage, PushEngage, Push Monkey, PushBots, PushAlert, Push.World, TITANPush, WonderPush, Notificare, PushNinja and Webpushify.
Some top alternatives to NotifyVisitors includes VWO Engage, PushAd, PushAssist, PushBots, PushAlert, Push.World, Notificare, PushNinja, SmartPush, LinkedIn Marketing Solutions and Notificationpro.