(Flickr/Twilio)
Twilio CEO Jeff Lawson.

Twilio’s one of those services you’ve been using without even realizing it.

For example, when Uber sends you a text message after a driver accepts a request or the ride arrives, it relies on Twilio’s technology to do it. The number you call to reach the driver is a temporary, one-time number created by Twilio too. Uber simply has to integrate Twilio’s software code into its app to make it happen.

Other services that use Twilio’s solution for similar purposes include Lyft, Airbnb, and Match.com. Even big companies like Coca Cola, Home Depot, and Nordstrom use Twilio to build their own sales and customer-service apps, or call-center infrastructure.

“Developers use us to create better communications in their apps,” Twilio’s CEO Jeff Lawson told Business Insider.

What Twilio builds is a piece of software code called an application programming interface (API) that developers can easily plug in to their own apps or websites to enable a variety of communication features, like text messages, phone calls, or even video chat.

Its ease of use and cost efficiency is making it a huge hit, especially with the growing number of developers looking for ways to quickly add communication features to their services. (Think of all the dating apps and on-demand services, or the smart devices that trigger all sorts of notifications.)

Twilio may not be a household name like an Uber or an Airbnb, but it’s certainly become one of the most popular tools used by developers these days. According to Lawson, more than 700,000 developers have used Twilio’s platform so far.

“When we started in 2008, we were consistently told by a lot of people that you can’t build a company around developers,” Lawson said. “But our model allows developers to build the right thing so the company can actually expand and become a meaningful business.”

Investors are buying into it too. Late last month, Twilio raised a massive $130 million round from T. Rowe Price and Fidelity, which Lawson confirmed made his company one of the $1 billion "Unicorn” startups.

The rise of 'no stack' startups

(Youtube/jpdc hd)
Uber uses Twilio's API to enable phone calls between the user and driver.

Services like Twilio have also been fueling the rise of the so-called "no stack" startups.

If startups in the past tried to build everything from the ground up, now a lot of them just focus on their core services, while borrowing underlying technologies — like Uber does with Twilio — for other functionalities.

Union Square Ventures’ Andy Weissman explained this in a recent blog post: