
Here is a list of known software using Flask in some sort of a way.
Flask is powerful micro framework that anyone wants to use it, so it’s not a secret that even big companies, like Reddit, use it in some capacity!
- Zillow (no official info, only usage mentioned https://stackshare.io/zillow/zillow) is a prominent online real estate marketplace used for buying, selling, renting, and financing properties.
- Reddit (no official info, only usage mentioned https://stackshare.io/reddit/reddit) is a social news aggregation, web content rating, and discussion website where registered members can submit content, such as text posts or direct links.
- Netflix (no official info, only usage mentioned https://stackshare.io/netflix/netflix) is a widely popular streaming service with a vast library of movies and TV shows available for online viewing.
- Trivago (no official info, only usage mentioned https://stackshare.io/trivago/trivago) is widely known for its hotel search platform.
- Pintrest (API endpoints, but last documented information about it is over 7 years ago https://www.quora.com/Is-Instagram-NASA-and-Pinterest-still-powered-by-Django-framework, and currently Django is listed as main API Framework, usage in internal tools last mentioned Flask in 2019 https://stackshare.io/jamesman11/decisions/103168682683990126)
- Lyft (only for logging, mentioned in 2018 https://stackshare.io/stackbot/decisions/102366436228454685)
- AirBnB (official package for Flask but last developed 2016 https://github.com/airbnb/Flask-AppBuilder)

Looking at the above list we can only see what these companies will show us, so there is great probability that there are other massive projects based on Flask! If you know them, share it in comments, preferably with link to source!
Thanks for reading!
