Amazon.com Inc. and other retailers are on pace to sell more products online than ever this holiday season, aided by early promotions and investments in delivery systems that helped avoid the widespread shipping delays of last year.

Web sales rose 14 percent from Nov. 27 to Sunday, consulting firm ChannelAdvisor Corp. said this week. That's roughly in line with comScore Inc.'s November forecast that online purchases would gain 16 percent to $61 billion during the three months through December. The total may include $7.9 billion in mobile sales, comScore said.

Amazon.com hired more workers and opened distribution centers to get goods to customers faster. United Parcel Service Inc. and FedEx Corp. also stepped up hiring, updated technology, and spent on infrastructure to absorb the growth.

Consumers, aided by lower unemployment and cheaper gas, responded to pre-Thanksgiving promotions instead of splurging at the last minute, something that contributed to last year's delivery delays.

"Shoppers were aware of last year's problems, and the e-commerce companies and shipping companies were prepared," said Jarrett Streebin, chief executive officer of EasyPost, a San Francisco company that helps retailers coordinate labels and tracking with delivery companies. "So far, it looks like everything went really well."

On Christmas, consumers went online to buy music, applications, and other content for smartphones and tablets they received as gifts. Online spending increased 8.3 percent Thursday from a year earlier, IBM, Corp. said Friday. That compares with last year's Dec. 25 growth rate of 17 percent.

The slowing growth on Christmas follows a broader trend of a longer shopping season with spending less concentrated on any particular day, said Jay Henderson, IBM's strategy program director.

"Consumers are spreading their spending out," he said. "Overall, shopping is going to be strong for the whole period."

Sales from third-party sellers on Amazon.com rose 20 percent from Nov. 27 to Sunday, according to ChannelAdvisor.

Retailers did a better job getting orders to customers on time this year, said Kevon Hills, director for research at StellaService, which monitors customer service at e-commerce companies. There were fewer warehouse bottlenecks, and retailers communicated better with delivery companies this year, Hills said.