New York, Dec 29 : As online shopping boomed this year amid Covid-19, Amazon has said that this holiday season has been the best ever for independent businesses selling on the marketplace with worldwide sales growing over 50 per cent compared to the same time period last year. Nearly all of third-party sellers are small and medium-sized businesses, the company said on Monday. "We invested billions of dollars to help small- and medium-sized businesses continue to grow and to help keep employees safe and deliver products to customers - including more than $2.5 billion in bonus pay to front-line workers," Amazon said in a blog post. The company said it invested more than $18 billion to help independent businesses grow their sales on Amazon this year. The e-commerce platform said it also spent more than $100 million on new promotional activities to help small businesses connect with customers beginning with Prime Day and continuing through the holiday season. The company also designed new ways for small businesses to reach customers with a dedicated support small storefront encouraging customers to shop small businesses by region or category, and allowing customers to meet the business owners. "When our customers - including healthcare workers on the front lines - most needed essential supplies, our teams and partners went above and beyond to stock and deliver those items," Jeff Wilke, CEO Worldwide Consumer at Amazon, said in a statement. Amazon also faced criticism from current and former employees who alleged that protection measures against Covid-19 lacked in warehouses. However, Amazon said that it invested $10 billion to help keep employees safe and deliver products to customers throughout 2020. "When it became clear that Covid-19 testing was going to be important, Amazonians across the company moved quickly to build our own testing capacity so we could help protect employees and deliver products to customers," Wilke said. /IANS