Plopsy

Plopsy is an in-game online store introduced in The Sims 4: Nifty Knitting Stuff, where Sims can buy and sell several different kinds of crafts across many different skills in The Sims 4. It is accessible from Sims' phones and computers.

Overview
Sims pay a small fee of §10 to list an item on Plopsy. It will remain listed for a maximum of three days if nobody makes an offer for it. Otherwise, if there are offers, players can decide to accept the best offer for them, and send the item through the mail to the buyer. A few days after sending it off, the buyer will leave a review on the seller's account.

Sims who decide to buy an item from Plopsy instead will have it immediately placed in their inventories. Items purchased in this way cannot be relisted on Plopsy, but they can be sold in other ways, such as in the inventory interface. Plopsy's storefront refreshes every hour.

List of crafts that can be sold

 * Alchemical potions
 * Fabricated candles
 * Herbal remedies
 * Knitting projects
 * Paintings
 * Photographs
 * Woodworking crafts

Trivia

 * Plopsy seems to be inspired by the real life, craft-sharing website Etsy.