RunJS is a free online front-end editor that allows users to create and share HTML, CSS, and JavaScript code snippets. With this tool, users can write code or markdown notes without the need to switch between browser tabs or applications.

One of the main features of RunJS is its seamless integration with the browser. Users can easily access the editor without leaving their current browsing session. This makes it convenient for developers and learners who want to experiment with code while reading technical articles or tutorials.

Another notable feature is the recent update that allows users to paste code directly into markdown. This makes it easier to create documentation or share code snippets in a more organized and readable format.

Overall, RunJS is a useful tool for front-end developers and learners who want a convenient and accessible way to write, edit, and share code snippets without the need for additional software or switching between browser tabs.