What's great about short stories? Well, for one thing you can read the whole thing in one sitting! Sometimes there are books of story collections by many authors, all around one theme (scary stories are common!), sometimes there are books written by one author with a group of linked stories. There are lots of great stories you can find online for free or for a small price.
Look Both Ways: A Tale Told in Ten Blocks - Jason Reynolds
Take the Mic: Fictional Stories of Everyday Resistance
Oddly Enough - Bruce Coville (on Hoopla)
Perilous Princesses - (on Hoopla)
Guys Read series (on Hoopla)
Tales from the Fringe of Fear (on Hoopla)
Terrifying Tales to Tell at Night (on Hoopla)
The Arabian Nights (on Hoopla)
Flying Lessons & Other Stories
The Hero Next Door
Behind the Song (on Hoopla - with a Spotify playlist)
Steampunk! (on Hoopla)
Stupid Perfect World (novella on hoopla) - Scott Westerfeld
Black Enough - ed. by Ibi Zoboi
How I Resist
His Hideous Heart
Open Mic: riffs on life between cultures in ten voices - ed. by Mitali Perkins
Fresh Ink
Skeleton Crew by Stephen King
Celebrate Short Story Month With Free YA Short Stories Online
13 Young Adult Anthology and Short Story Collections - Epic Reads, May 28, 2019
(Wh)Y A(n) Anthology - Book Riot, Feb. 2, 2020