Are you one of Earth's three billion urban dwellers? Then there's a fair chance you're limited on space. And in case you don't subscribe to Marie Kondo's do-away-with-everything-that-doesn't-spark-joy manifesto, you probably have a lot of stuff squirreled away that you no longer have room for but aren't quite ready to part with. Enter the savior of the uncompromising hoarder: space-saving furniture. We've compiled 21 lightweight, multifunctional, and adjustable items that will perform spatial alchemy on any apartment. Their beauty is in their ability to transform, contain, and enlarge. You can shop them all right now, they fit into every budget (ahem, Josef Albers Nesting Tables gladly rub shoulders with a $3 shelf from Flying Tiger), and they will give your Container Store-ridden apartment a much-needed update.