Companies that create mobile apps and cloud services can be volatile investments, due to an emphasis on high revenues over profits, lofty valuations, and poorly diversified business models.

But they can also be incredible growth plays for patient investors who can stand the volatility. Let's examine three risky mobile stocks which offer potentially high rewards -- Momo (NASDAQ:MOMO), Twilio (NYSE:TWLO), and Zynga (NASDAQ:ZNGA).

Momo

Momo, often called the "Chinese Tinder", rallied nearly 270% over the past 12 months. Momo's social app lets users find and contact nearby users, watch live video streams, buy virtual gifts for their favorite broadcasters, and play social games. Its monthly active users (MAUs) rose 16% annually to 81.1 million last December.

Momo's mobile app.

Momo's mobile app. Source: Google Play.

The growth of Momo's live streaming platform enabled its year-over-year revenue growth to accelerate over the past three quarters. Its revenue rose 313% to $553.1 million in 2016, and analysts anticipate 122% growth this year.

Thanks to the high-margin business of user-generated videos and virtual gifts, Momo's non-GAAP net income surged 469% to $177 million in 2016, and its GAAP net income rose more than tenfold to $145.3 million. Analysts expect its non-GAAP EPS to grow 80% this year. Those are stunning growth figures for a stock that trades at 36 times earnings, compared to an industry average of 38 for internet information providers.

There were recent concerns that new video streaming rules in China would throttle Momo's growth. However, Momo already holds the Internet Audio-Visual Program Transmission License (which is currently being enforced) -- so the issues facing Weibo and other sites shouldn't impact Momo.

Twilio

Twilio's cloud-based service processes SMS messages, voice calls, video, and other content for mobile apps. Developers simply integrate Twilio's APIs into their apps to add these services -- which is easier than building them from scratch.

A smartphone, laptop, and tablet surrounding a cloud-shaped cutout.

Source: Getty.

Twilio's revenue rose 66% to $277.3 million in 2016, and analysts expect 30% sales growth this year. It still isn't profitable by either non-GAAP or GAAP measures, but that's common in the cloud SaaS (software as a service) market where the high costs of developing new products and securing new customers are tough to balance with competitive prices.

Twilio rallied 10% over the past 12 months, but it's still weighed down by concerns about its slowing sales growth and customer concentration. A secondary offering spooked investors last year, and the recent bombshell that Uber, its top customer, would wean off its services exacerbated the pain. Twilio also isn't cheap at 9 times sales, compared to the industry average of 6 for application software makers.

Nonetheless, Twilio remains a "best in breed" niche player that serves big customers like Facebook and Amazon. Looking ahead, Twilio could evolve into a diversified cloud services company or be acquired by a larger tech company -- so it could be smart to buy this stock while it's being ignored by the market.

Zynga

I've never been a fan of Zynga (NASDAQ:ZNGA), but the mobile game maker seems to have turned a corner. Last quarter, its mobile daily active users (DAUs) rose 16% annually to 18 million last quarter, lifting its mobile revenue by 19% and giving it a second straight quarter of positive annual sales growth.

Farmville: Tropic Escape.

Farmville: Tropic Escape. Source: Google Play.

Zynga's revenue dipped 3% to $741.4 million in 2016, but "bookings" -- the total purchases of virtual products (reported as deferred revenue) recognized over the estimated time it takes to consume them -- rose 8% to $754.5 million. Analysts, who track Zynga's bookings instead of revenue, expect that figure to rise 12% this year.

Zynga's turnaround can be attributed to robust growth at Farmville and Words with Friends, as well as the growth of Zynga Poker -- which offset its lower ad sales. On the bottom line, Zynga's adjusted EBITDA (including the impact of deferred revenue) fell 40% annually to $48.8 million in 2016. Zynga is unprofitable on a GAAP basis, but it's trying to cut costs by expanding its higher-margin online multiplayer titles and other services.

Zynga is still a work in progress, but its price-to-sales ratio of 4.5 is lower than the industry average of 6 for video game companies. This makes it an interesting turnaround or buyout play for more daring investors.

Leo Sun owns shares of Amazon and Twilio. The Motley Fool owns shares of and recommends Amazon and Facebook. The Motley Fool recommends Momo, Twilio, and Weibo. The Motley Fool has a disclosure policy.