It’s Free Shipping Day today, and more than 1,219 U.S. retailers are offering free standard delivery on orders in time for Christmas with no order minimum. Here is a full list of all participating retailers, which include holiday season stalwarts like Macy’s (M), J.C. Penney (JCP) and Barnes & Noble (BKS).

(One notable exception is Amazon.com (AMZN), which offers free two-day shipping for Prime Members. As for Walmart, (WMT) it is the only time this season it is waiving the $50 order minimum even though its closest rivals Target (TGT)and Best Buy (BY) have required no minimum order size for free shipping throughout the holidays. Walmart has also been aggressively pushing in-store pick up.)

Beyond free shipping, many retailers are offering other cost-free services on Free Shipping Day. For instance, Neiman Marcus Group’s Bergdorf Goodman store, which has no order minimum (not much of what they sell is cheap anyway), is offering free two-day expedited shipping. And Lululemon Athletica (LULU) is offering free returns.

On top of trying to create buzz just ahead of the biggest shopping day of the season on Saturday, Dec. 17, (the last full Saturday shopping day before Christmas), there are practical considerations for this as well, namely avoiding e-commerce pandemonium.

As Fortune reported earlier this week, this year, many major retailers including Kohl’s (KSS) and Macy’s (M) have set the deadline earlier this year for placing an order and being sure it gets delivered by Christmas, in a move aimed in part at handling the record volume of packages retailers and shippers expect to handle.

Data provided by StellaService show that only four retailers (Apple, Nordstrom, HBC’Saks Fifth Avenue and Office Depot) this year are letting shoppers place orders as late as Dec. 22 or 23 (next Thursday and Friday) for on-time delivery via standard shipping, compared to 12 last year.

Smooth online orders are key for to a successful holiday season. Online sales are poised to grow 11% this holiday season, according to Adobe Digital Insights and retailers, as well as shippers like FedEx (FDX) and UPS (UPS) want to front load as much of their delivery volume as much as possible, lest they overload their capacity to deliver packages up until the Christmas deadline.

UPS has said expects to deliver more than 700 million packages this holiday season, a 14% jump over last year. FedEx foresees a 10% increase. The less they have to process on Christmas Eve, the lower the risk of a snafu or a snowstorm creating Christmas Chaos.

Free Shipping Day in a nutshell:

More than 1,200 retailers are participating;

To count as a participant, an e-retailer must has to offer free shipping with no minimum purchase on Dec. 16, 2016 with delivery by Christmas Eve.

Retailers ranging from discounters like Target to luxe chains like Neiman Marcus are taking part.

The collective promotion began at midnight and end the end of Friday.

Many retailers offer special deals beyond free shipping, such as discounted expedited shipping and free returns.