Excel is the biggest competitor for most SaaS companies.
The economy runs on it.
Your customers probably still use it.
And it's had a 23 year head start on the market.
The unbundling of Craigslist created billions of dollars in value for startups. Whether it was Stubhub <> Tickets or Tinder <> Missed Connections -- there are plenty of examples of consumer companies created on the back of the Craigslist giant.
For SaaS - that giant is Excel/Spreadsheets.
Here's a graphic showing just some of the companies that have been unbundling elements of Excel to create millions (sometimes billions) of dollars in value.
And here's a deeper take on the opportunity: http://bit.ly/2HD5VXH