Can you list the most commonly used online marketplaces for used goods by country, e.g. Craigslist for USA
Sort the list by volume.
Sure! Here are some commonly used online marketplaces for used goods by country, sorted by volume:

United States:

* Craigslist
* Facebook Marketplace
* eBay
* OfferUp
* Letgo

United Kingdom:

* Gumtree
* eBay
* Facebook Marketplace
* Preloved
* Shpock

Canada:

* Kijiji
* Facebook Marketplace
* Craigslist
* VarageSale
* Letgo

Australia:

* Gumtree
* Facebook Marketplace
* eBay
* Trading Post
* Carousell

Germany:

* eBay Kleinanzeigen
* Shpock
* Facebook Marketplace
* Quoka
* Markt.de

France:

* Leboncoin
* Facebook Marketplace
* eBay
* Rakuten (formerly PriceMinister)
* Vinted

Japan:

* Mercari
* Yahoo Auctions
* Rakuten
* Craigslist
* Facebook Marketplace

Note that this list is not exhaustive and there may be other popular marketplaces in each country.
Can you provide URLs for each?
Sure. Here are the URLs:

Craigslist				https://www.craigslist.org

Facebook Marketplace		https://www.facebook.com/marketplace

eBay					https://www.ebay.com

OfferUp					https://offerup.com

Letgo					https://offerup.com (Letgo became a part of OfferUp in 2020)

Gumtree					https://www.gumtree.com

Preloved					https://www.preloved.co.uk

Shpock					https://www.shpock.com

Kijiji						https://www.kijiji.ca	

VarageSale				https://www.varagesale.com

Trading Post				https://www.tradingpost.com.au

Carousell				https://au.carousell.com

eBay Kleinanzeigen		https://www.ebay-kleinanzeigen.de

Quoka					https://www.quoka.de

Markt.de					https://www.markt.de	
	
Leboncoin				https://www.leboncoin.fr

Rakuten					https://www.rakuten.com

Vinted					https://www.vinted.com

Mercari					https://www.mercari.com

Yahoo Auctions			https://auctions.yahoo.co.jp