Replit

Replit is a cloud development environment combined with an AI agent that runs entirely in your browser. It's made by the company of the same name, which grew from an online code editor into one of the best-known platforms for building apps with artificial intelligence. It suits beginners and non-technical founders who want to validate an idea quickly, as well as experienced developers who need to prototype without fiddling with local setup.

It works simply: you tell the agent what the app should do, and it writes the code, installs the libraries, sets up the database and deploys the whole thing to the web. The input is your plain-language description, the output is a working, publicly available app or site. You watch the progress in real time and can step in at any moment, tweak the prompt or edit the code directly.