Several types of visa that extendable :
Visa on Arrival (VOA)
For International Travelers who enter Indonesia by VOA can get one extension for 30 days, giving a total stay of 60 days. After 60 days, International Travelers must exit Indonesia.
Single Entry Visa (B-211)
Single Entry visa holder allowed to enter Indonesia with a permit of 60 days, and it is extendable for 60 days (twice) giving a total stay of 180 days.