Robinhood - Free stock trading service.
PagerDuty - Cloud based monitoring service
Rally Rd. - Invest in blue-chip classic cars like stocks
One Call Now - One Call Now's message notification delivers automated phone calls, SMS text messages and emails within moments to any group.
Freetrade - Invest in stocks & ETFs for free, get started in seconds.
OpsGenie - Alerting and On-Call Management for Dev&Ops Teams