The global e-commerce market is projected to grow from $3.54 trillion to $6.54 trillion between 2019 and 2023, according to eMarketer. During that same period, e-commerce's share of all retail revenue is projected to go from 14% to 22%. That's just two ways of saying leading e-commerce companies look to have plenty of room to grow over the next five years.

Investors looking for bargains might be nervous about buying e-commerce stocks as the market hovers near historic highs, but three high-growth companies in this sector -- JD.com (NASDAQ:JD), Etsy (NASDAQ:ETSY), and Square (NYSE:SQ) -- deserve closer looks.

Tiny parcels on a laptop keyboard.

Image source: Getty Images.

1. JD.com: China's biggest retailer

JD.com is China's largest direct retailer and second-largest e-commerce player after Alibaba. It struggled last year as its revenue growth decelerated, its expenses rose, and CEO Richard Liu was hit by a troubling rape allegation.

However, JD's revenue growth accelerated over the past two quarters, its operating margin stabilized, and the charges against Liu were dropped. The profitability of its logistics platform improved as it scaled up and offered its services to other companies.

That platform continues to evolve with autonomous warehouse robots, delivery vehicles, and drones. JD is reportedly mulling a spin-off IPO for the logistics unit, which could raise up to $10 billion and improve JD's long-term profitability.

JD's revenue rose 29% annually last quarter, as its number of annual active customers grew 10% to 334.4 million -- marking its strongest growth in four quarters. JD attributed that growth to its expansion across lower-tier cities, and the launch of its discount platform Jingxi, which challenges Pinduoduo in the low-end market.

Analysts expect JD's revenue and earnings to rise by 19% and 38%, respectively, next year. Those are solid growth rates for a stock that trades at just 26 times forward earnings, and it indicates that JD isn't struggling against competition from Alibaba, U.S.-China trade war pressures, or the economic slowdown in China.

2. Etsy: The top artisan marketplace

Etsy, the online marketplace for handmade goods, withstood competition from Amazon (NASDAQ:AMZN) with its first mover's advantage, lower seller fees, and more relaxed rules regarding promotional tools like mailing lists and links to personal sites. That's why its number of active sellers grew 27% annually to 2.6 million last quarter, as its number of active buyers rose 21% to 44.8 million.

That growth can be considered a reaction to Amazon's growth as a mass retailer: A recent survey by Faire found that 37% of millennial women in the U.S. preferred handmade gifts over mass-produced products, and 65% of all millennial shoppers preferred to buy holiday gifts from independent retailers instead of mass retailers.

Etsy's core business remains strong, but its growth notably decelerated over the past year. Investors also have lingering concerns about its dipping take rate (its revenue retained from each transaction) and its acquisition of Reverb, an unprofitable marketplace for musical instruments.

Handmade bead necklaces.

Image source: Getty Images.

Despite those challenges, analysts still expect Etsy's revenue and earnings to grow 26% and 21%, respectively, next year. Etsy's stock isn't cheap at 56 times forward earnings, but I believe it justifies that premium with its resilient growth, brand recognition, and growing appeal as an alternative to Amazon, which is struggling with ongoing quality control issues at its third-party marketplace.

3. Square: A "one-stop shop" for e-commerce services

Over the past decade, Square expanded its digital payments ecosystem beyond card-reading gadgets with its Cash App for peer-to-peer transfers, bitcoin and stock trades; payroll, website, and e-commerce tools; and a financing arm for small businesses.

In short, Square became a "one-stop shop" for bringing an offline business online. Square still faces plenty of competition from companies like Shopify and PayPal, but its consistent streak of double-digit revenue growth indicates that there's still plenty of room to grow.

Square's revenue rose 44% annually last quarter as its GPV (gross payment volume), or the value of all payments on its platform, grew 25% to $28.2 billion. Its subscription and services revenue -- which mainly comes from its Cash App, Instant Deposit, and Square Capital units -- surged 68% and accounted for 22% of its top line.

Square's stock only rose about 10% this year as the bulls and bears battled it out. Analysts expect its revenue and earnings to rise 27% and 23%, respectively, next year -- but its forward P/E of 65 is a bit high relative to that growth.

Nonetheless, Square's core businesses are still firing on all cylinders, and it still has plenty of ways to expand its ecosystem, cross-sell new services, and lock in its merchants. Therefore, I think investors should accumulate shares of Square on any dips since it could grow significantly larger as the war on cash escalates.