There are dozens of stocks with market caps north of $1 billion that have more than doubled this year. Some of them will struggle to hold on to those gains, but there are some big winners in 2020 that will keep building on earlier gains. 

Twilio (NYSE:TWLO), Zoom Video Communications (NASDAQ:ZM), and DocuSign (NASDAQ:DOCU) are three high-flying growth stocks that continue to be attractive. Let's go over the reasons these three stocks could double again in the second half of this year.

The year 2020 growing from left to right with a green arrow rising higher above.

Image source: Getty Images.

Twilio

Investors are starting to know about Twilio, even if mainstream consumers have no idea that it's the company making their apps more efficient. Twilio is the leading provider of in-app communication tools, arming developers with ways to improve engagement. Whether it's checking with the owner of the Airbnb villa you're eyeing for availability, or resetting your Hulu password, or letting you know that your ridesharing service has arrived, Twilio is what makes most of your favorite apps tick. 

Revenue grew 57% in its latest quarter, and its adjusted profit exceeded analyst expectations for the third consecutive period. It's not just app users who find Twilio engaging. Existing clients are spending 43% more on average than they were a year earlier. 

Zoom Video

No platform has had the kind of glow up that Zoom has experienced this year. The cloud-based videoconferencing specialist has gone from hosting as many as 10 million people a day six months ago to as many as 300 million a day now. 

Most of Zoom's customers are free accounts, and there's nothing wrong with that. Making it easy for corporate meetings and classroom sessions to go virtual on its platform will pay off in the long run as folks come to rely more and more on Zoom. But this isn't just a revolution of freeloaders at its doorstep. The number of customers spending at least $100,000 a year through Zoom has nearly doubled over the past year. 

Momentum is a beast here. Revenue soared 169% in its latest report, more than double what it was targeting for the quarter just a few months earlier. Its full-year guidance, which now calls for $1.775 billion to $1.8 billion in revenue, is more than double what it was modeling back in March. Companies want to get folks back into the office, and schools long for the in-class experience, but there will now be a strong Zoom component to these businesses. 

DocuSign

Wet signatures are all wet these days. Electronic signatures are taking over as a way to sign forms, contracts, and other documents. And DocuSign is the undisputed top dog in this niche. It may not be growing as quickly as Twilio and Zoom, but it did come through with a 39% increase in revenue for its latest quarter with an even more encouraging 59% pop in billings. 

Momentum was already building for eSignatures before social distancing during the pandemic made them an industry standard, but the crisis is naturally speeding up the migration process for the platform. With DocuSign evolving into a more well-rounded document management giant (and revenue growth accelerating), it joins Zoom and Twilio as some of this year's top growth stocks with strong prospects to keep the gains coming through the next six months of 2020.