The eVOA is available to citizens of around 100 countries at the moment — Australia, Germany, Austria, UK, the Netherlands, France, Belgium, the US and Switzerland are definitely on the list. Most other European countries, Canada, and many Asian countries are included as well.
This list is updated by the Indonesian government from time to time, so the exact makeup can change. If you're unsure about your nationality or you're not a citizen of one of the countries above, just get in touch with us — we'll confirm for free, with no obligation, whether the eVOA works for you or whether you'll need a different visa (e.g. the C1).