There are some prerequisites:
- All code must use AMD-style require and define to load and create modules. Code that uses global references to Esri and/or Dojo modules is not supported.
- ArcGIS Online organization or ArcGIS for Developers account.
- JS API version 3.4 or later.
- Custom modules should define a package.json file that, at minimum, defines name and version properties.
Access the Web Optimizer here: http://jso.arcgis.com/