REPL.it is an online platform that allows users to write, run, and share code in various programming languages directly from their web browsers. It provides an integrated development environment (IDE) that supports languages like Python, JavaScript, Ruby, and many others, making it accessible for beginners and experienced developers alike. The platform also features collaborative tools, enabling multiple users to work on the same project in real-time. Additionally, REPL.it offers a community where users can share their projects, seek help, and learn from one another, fostering a supportive environment for coding enthusiasts.