Service Providers should implement IDP discovery, i.e., allowing subjects to choose their Identity Provider from all available/desirable ones, by integrating it within their application. See the REFEDS Discovery Guide for details on why and how. ACOnet recommends using one of these Free/Libre software projects, which can be integrated with most any software or website:
Contact ACOnet for help with integrating one of these implementations into your website.
Fallback discovery services
If all else fails you can make use of one of the central "fallback" discovery interfaces provided by ACOnet.
The SWITCHwayf software may be more familiar to subjects from ACOnet institutions since an older version had been in use at https://wayf.aco.net/ since 2007. This software still works (without its dynamic features) when JavaScript is disabled in the web browser (though not much else on the web will work in such a setup):
The DiscoJuice software has a more unusual look and feel but also provides additional features such as grouping (and limiting) IdPs by country or sorting suggested IDPs based on their distance via geolocation of the web browser. These DiscoJuice instances do not currently work when JavaScript is disabled:
Overview
Content Tools
Tasks