Most global online merchants are falling sort of the expectations of their international customers,

the latest X-Border Payments Optimization Index revealed.

According to the index from PYMNTS.com and Digital River online merchants with the highest performing cross-border ecommerce sites offer shoppers a variety of language, payment and currency options, as well as free shipping, rewards, country-specific address fields, a mobile-friendly web presence and easy checkouts.

Most global ecommerce sites underperformed and fell short in meeting the expectations of the international shopper.

The quarterly X-Border Payments Optimization Index measures how prepared merchants are to deliver a seamless and localized ecommerce experience to online shoppers outside their own country. The Index rated more than 180 online stores on a scale of 1 to 100 across 60 attributes such as shopping experience, payment options, loyalty and reward programs, and site navigation. The online stores were from 10 countries, including Canada, China, France, Germany, Italy, Japan, Mexico, Spain, the U.K. and the U.S.

Merchants only scored an average of 56, which means that most of their sites fail to make it easy for customers to complete cross-border purchases.

“With a $300 billion cross-border ecommerce opportunity at stake, merchants can’t afford to optimize some parts of their global shopping experience at the expense of others,” said Hayden Reed, Digital River’s senior vice president and general manager of Digital River World Payments. “Delivering a cross-border experience that is as convenient and familiar as purchasing from your neighborhood store requires merchants to take a holistic approach to building their ecommerce sites.”

Among the most significant findings of the index, 100 percent of the top 10 sites offer free shipping and mobile-optimized experiences for cross-border consumers. Only 20 percent of the lowest 10 scoring sites offer free shipping and 30 percent offer mobile.

Eighty percent of the top 10 scoring sites offer rewards and allow consumers to checkout in half as many pages as the 10 lowest scoring sites.

The U.S. remains the leader in cross-border ecommerce optimization. U.S. ecommerce sites scored an average of 64 out of 100 and excelled in online navigation, cost, payment and privacy attributes.

China ranked a close second with an average of 62. China-based sites excelled at offering localized currencies, languages and shipping destinations.

France took the last spot in the index with an average score of 49. The French sites offered fewer language options and currencies, and most required consumers to fit addresses into French-specific address fields, pay for shipping, and create a user profile in order to purchase.