No payment, no account required. The creator Lax1dude wrote the engine from scratch, but you still need a legitimate Minecraft license to download assets (though many users ignore this).
Because it runs entirely in a browser, it bypasses the need for the official Minecraft Launcher. This makes it incredibly popular for: eaglercraft minecraft
At its core, Eaglercraft is a port. The original Minecraft Java Edition is written in a language called Java, which requires a specific runtime environment (JRE) installed on your computer. Most school laptops, workstations, and Chromebooks block users from installing new software. No payment, no account required