There's a reason why Marie Kondo, renowned organizer and star of Netflix’s Tidying Up with Marie Kondo, has been such a runaway success. How many of your possessions give you that distinctive "spark of joy"? In all likelihood, you’re holding on to some stuff that doesn’t, and it’s high time you parted ways with it. What better way to do so than by selling your stuff on one of the many popular buy-and-sell apps on the market today?

Modern technology has created a massive digital yard sale, where can you can connect with potential buyers and sell your items for cash. And it works both ways; if there's something specific you want to buy on discount, you'll find no better garage sale than the one on the Internet.

Finding the best buy-and-sell groups or apps to sell stuff can be a lot of work, so we’ve done the hard part for you. Whether you’re looking to sell or buy, here are the 10 best selling and buying apps.

Selling

Letgo

Founded in 2015, Letgo is about sheer variety; everything under the sun is listed, from cars to houses to antique furniture. Exchange of items is done locally, at a place of your and the buyer's choosing—always do these types of meetups in public! The app has a notification and chat function that allows you to talk with prospective buyers without giving out personal information. Best of all, LetGo doesn't take a cut of any sale; they don’t handle money, period. It's up to you to close the deal, which, depending on how well you haggle, can be a major plus.

Poshmark

Launched in 2011, Poshmark is about everything pertaining to clothes and fashion accessories. As a buyer, you can browse through other users' digital "closets" and reach out to sellers directly to close deals. But where Poshmark really shines is as a seller: the buyer incurs the shipping cost per items, and as a seller, you get a free shipping label to the address you're delivering to, which means you're making extra money with less strings attached. Keep an eye on the weight, though; anything over five pounds means an extra shipping cost, and you'll have to pay the difference.

Carousell

If you're an expat in Singapore, Malaysia, Indonesia, Taiwan, Hong Kong, or Australia, then Carousell is the go-to buy/sell app. Founded in 2012, the company's mantra is "sell in a snap, buy with a chat." You can take up to four photos of a single item, and said items range from toys to cars to real estate is available. You can also join Carousell "groups," which can connect you to customers based on common interest, school, or zip code. Meetups and last-minute haggling via Private Chat happen on your terms.

DePop

With 11 million users and counting, DePop is aimed at the younger, trendy set; it's as much about interactivity and window shopping as it is about purchasing items. Depop markets itself as a cross between a second-hand clothing retailer and Instagram for "creatives," and its major users have the potential, just like Instagram users, to become celebrities in their own right. Buy, browse, and get inspired.

Facebook Marketplace

The benefits of Facebook Marketplace are baked into its name—it's Facebook, for heaven's sake. Everyone and their mother has an account, which means there are buyers out there for all of your old stuff. There's no charge, and you can start immediately; just log onto your Facebook app, click the Marketplace icon, and you're good to go.

Buying

CPlus

Craigslist is a massive, but intimidating experience—a digital, freewheeling flea market if there ever was one. Free app CPlus takes an ugly, monotonous site (no offense), and makes it more interactive and streamlined. Everything you can do on Craigslist, you can do through CPlus. Plus, there are options for multiple city searches, and to organize your search results by map. It can even double as a dating app, if you're lucky!

5Miles

Craiglist's direct competitor, 5Miles functions similarly to its rival does, but with the promise of additional safety and security. You "book" mutual appointments through the app, users are "verified," and both buyers and sellers can leave ratings about their experiences. You know who to trust, and you know that you're talking to a person rather than a bot or a scammer.

Tradesy

The most high-end buy-and-sell app on this list, Tradesy specializes in gently used, name brand fashion. If you're in the market for some Jimmy Choos or Louboutins, or if you want up to 90 percent off a Chanel bag, Tradesy has you covered. Best of all, a team of experts authenticates the items; if you get ripped off, Tradesy will issue a full refund on your purchase.

VarageSale

A small site, relatively speaking, the most appealing aspect of VarageSale is that everyone active on the site is verified; in fact, becoming verified is part of the sign-up process. Users must confirm their identity and location via their Facebook profile and be manually approved by an administrator before they can buy or sell a single thing. You might not be able to find everything you need immediately, but when you do, you can rest assured that you won't be ripped off.

BookScouter

If you're a college student, then you know the pain and wallet-breaking agony of the textbook marketplace; a vital textbook could run you hundreds of dollars. BookScouter partners with multiple vendors to finds the most discounted used textbooks available. There are also options for 90-day rentals for students who are on a tighter budget.