SAN DIEGO — It may not have the same cachet as Black Friday or Cyber Monday, but an unofficial retail holiday, Free Shipping Day, will be the equivalent of a Christmas miracle for shopping slowpokes.

In its eighth year, Free Shipping Day, which falls on Friday, offers last-minute shoppers the kind of deal that may be too good to pass up: free shipping with guaranteed delivery by Christmas Eve at participating online merchants.

This year, more than 900 retailers have signed up to participate in the e-commerce event, offering time-crunched consumers a panoply of gift options. The expansive list, available at Freeshippingday.com, touts retail giants such Target and Wal-Mart, and smaller brand names including Road Runner Sports and The Body Shop. Some merchants are offering additional discounts, with coupon codes appearing on the website beginning Friday at 12:01 a.m. Eastern time.

"Being marketers, we look at Cyber Monday and Black Friday as holidays for early-bird shoppers," said Luke Knowles, 37, the creator of Free Shipping Day and the founder of its sister site Freeshipping.org. "Free Shipping Day is a holiday for procrastinators."

Knowles said he initially put together the day in 2008 because free shipping wasn't common at the time and he believed online shopping was peaking too early in the year. That year, he was able to secure around 250 merchants, including Target and Pottery Barn brands, to offer free shipping deals.

Now the Free Shipping Day website typically attracts between 250,000 and 300,000 visitors on the big day, Knowles said.

"In the early years, the delivery deadline may have been an issue," he said. "But a lot of these retailers can ship three days (after the 18th) and still get (orders) there by Christmas Eve."

In terms of sales, the man-made day is expected to rake in $1.35 billion from online shoppers, and will be the second-to-last billion-dollar e-commerce day of the season, according to Adobe's Digital Index, which aggregates data from more than 4,500 U.S. retail websites. Though impressive, the figure amounts to a fraction of the $3 billion online consumers spent on Cyber Monday and the $2.7 billion they electronically shelled out on Black Friday.

But the billion-plus sum is proof that retailers can push the online holiday shopping season later into the year — and offer a little peace of mind.