Hello, Dilipkumar Jadhav wrote: No there's not really an upper limit. Just the import of the XAR can be limiting, since XWiki right now has to load the whole XAR in memory. Even this should not be a problem if you stay reasonable (for example, the skin editor application http://code.xwiki.org/xwiki/bin/view/Applications/SkinEditorApplication embeds the dojo library + bespin code). Couples of mega bytes is definitely not an issue. Applications (or front-end extensions/plugins), are free to use any library they need. The good practice is to use the bundled libraries (prototype, scriptaculous, etc) versus non-bundled libraries (jquery, dojo or other) as much as possible, since it makes the pages smaller and it does not force the client to load a new file. Of course, this is not always possible, for example when you want to use a tiers library which itself is based on a non-bundled library like jquery (like in your case). If you have to do this, right now there are too approaches : either you include the library as a JSX (so paste the code in a JSX object in a wiki document), or you attach the .js file to the document and inject the needed <script> tag from a JSX extension that makes use of this library (something like : document.write('<script src=$doc.getAttachmentURL("mylib.js") ...') ; which is the preferred way for big libraries, since JSX objects have a limit in terms of content size. In the future we will probably makes it easier for extensions to require external libraries from attachments, with a new SX plugin for example. The conclusion is that it's better to use prototype if your need is a framework for DOM manipulations, AJAX, OOP-style javascript, etc; because it's bundled already in every page XWiki renders ; and use other libraries only when you really need it, of course taking care they are compatible with the ones bundled by default (there should be no problem with jQuery as far as I know, and there is non for sure using dojo). Hope this helps. Jerome