Not to be confused with Replot.
Repl.it is an online integrated development environment created by Amjad Masad and Max Shawabkeh (former Google engineer, current game developer) supporting more than 50 programming languages. Repl.it started as a personal project between Masad and Shawabkeh in the middle of 2009. Max later left for unknown reasons. Repl.it also has a Discord Server.
Repl.it supports a wide array of languages and those that are officially supported can be viewed at the language list; however, there are languages that run on repl.it that have not been officially announced or are not listed. The most popular is the makefile language, Polygott.
Repl.it has thousands of users using it, and a large community. It is possible to see them in Repl.it Talk and Repl.it Discord. Repl.it frequently hosts challenges for its users with prizes.
Repl.it is also often called Replit (without the period).