90+ nationalities can get now online a Visitor Visa (known as Visa on Arrival). You can still purchase it also at the airport in the arrival hall upon arrival.
This Visa is Valid for 30 days, and can be extended ONCE, for another 30 days (also online). You can still also get this Visa upon arrival in the arrival hall at the airport. If you get the Visa at the airport (or harbours) then cannot extend this visa online, but you can still extend it for another 30 days with the help of an agent (or by going twice to the immigration office.
For more information, please contact the local Indonesia Embassy in your country .