You mean the mods, right? Well, having full mod support on the web version is going to be difficult. Browsers just make it hard to do mods. Currently, even a simple thing like a language mod has to be hosted on a server somewhere so that the web version can install and use it. As for storage space concerns, the game still needs to download and install it somewhere, so it’s using your storage space. Mods are a few kilobytes at the moment.