Originally known as the "Barista AU", this form of fanwork began life on Livejournal but has since become popular across the board in fandoms. It is especially popular on fanwork-heavy sites such as Archive of Our Own, Tumblr, and Wattpad.
The origin of this AU is uncertain but it seems to have first popped up within the NSync and Backstreet Boys Real-Person Fic communities in 2001. It later spread amongst Stargate Atlantis fans, and then ultimately other fandoms took note. The AU became especially prevalent starting in the early 2010s.
Coffee shops are known for a comfortable, casual and urban feel that lend themselves well to all sorts of shenanigans. The default in this AU is that it's a shipping fic where one half of the pairing is a barista and the other half is a customer; this type of AU is popular due to it being a form of Meet Cute. Another popular form is for the coffee shop to be a Local Hangout where most of the cast either visit or work at. The third most common form is where both characters are baristas who work together.
If a character loves coffee, then expect a lot of coffee shop AUs involving them.
The "Coffee Shop AU" is often seen as a counterpart to the High School A.U.. Due to writers drawing from life, teenagers will favor high school stories while young adults like coffee shop works. As a similar result, this AU often overlaps with the College AU fanwork: The characters either work at the coffee shop to help get through college or coffee shops act as the Local Hangout for college students.
- Amongst the bandom, Panic! at the Disco and My Chemical Romance fans are especially prone to this sort of AU. Panic! At The Disco's Jon Walker once worked as a barista prior to joining the band. My Chemical Romance fans know of Gerald Way's love of coffee, and thus he frequents coffee shops a lot in fanfics.
- Kirby's Dream Cafe is a Kirby take on this. In it, Kirby's Dream Cafe is due to be demolished by Haltmann Works Company, who wish to turn it into a mall. Kirby and his friends have to stop them.
- Widowmaker writes about herself and Tracer in one of these in this installment of the Overwatch AWNN series.
- Two canon examples in Bungo to Alchemist in the form of Café Royale and Café Noir events, in which writers basically go to explore and purify Coffee Shop AU Fics, the latter of which is written by Kume Masao.
- High Fantasy webcomic Exiern had an Overly Long April Fools Gag in 2010 when it was suddenly re-tooled as a group of trendy twentysomethings hanging out at a coffee shop.
- Service with a Smile is a Web Animation/RWBY fanfic where Jaune Arc opens a coffee shop in Vale after his forged transcripts are rejected by Beacon Academy.
- Steven Universe: The show itself pokes fun of this. In "Same Old World", while flying over Empire City (their world's version of New York City) with Lapis, Steven mentions that she could move there and work at a coffee shop:
Lapis: So what does happen in Empire City?
Steven: Well, if you moved here you could get a cool apartment and be a single Gem taking on the big city. You'd have a fun job at a local coffee shop and come home to a wacky roommate...
Lapis: I have no idea what you're talking about.