I've been in awe of Hubspot's success for years now (full disclosure - CloudRevenuePartners is a Hubspot user and Gold Partner),

• serious, serious growth for years now - in less than 10 years - 2018 $513m revenue
• 60,000+ customers 
• selling SaaS (new definition of SaaS further down this blog) to the SMB!!!! I've been told hundreds of times from VC's "it's impossible to make a business selling SaaS to the SMB"
• a massive following including 10's of thousands at their annual Inbound conference