All travelers to Indonesia must be in possession of a Passport that is valid for at least six (6) months from the date of arrival, and have proof (tickets) of onward or return passage. By Presidential Decree of 21 of 2016 dated on 2 March 2016 on Visa Free, replacing Presidential Regulation Number 104/2015 on Amendments to Presidential Regulation Number 69/2015 on Visa Free, Indonesia now provides special Short Stay Visa Free facilities for tourists who are nationals of a total 169 countries who wish to travel to Indonesia.

Tourist Visa Free Facilities are valid for 30 days, are non-extendable and cannot be transferred into any other type of of stay permit.

The visa exemption facility can be used for tourism, family visit, social visit, art and cultural, government duty, to deliver a speech or attend a seminar, international exhibition,meetings with head office or representative office in Indonesia, or transit.

source: http://www.indonesia.travel/gb/en/before-you-go/visa-immigration

The government has a tourist visa system with three different categories:

I. Visa-On-Arrival (VOA)

The Pay for Visa-On-arrival (VOA) system applies for citizens of certain nations.

Please visit the Indonesian Embassy website for your country, to see the full list of nations and which international gateways you can require the visa from.

The cost of the 30-day (only) tourist visa is US$35/person for a 30-day visa and US$10/person for a 3-day visa. The fee must be paid in cash (no credit cards) on arrival at the airport.

Visitors from countries with visa-on-arrival facility will have to go to a special counter to have their passports stamped with the on-arrival visa before going to the immigration clearance desk. The VOA visa is NOT EXTENDABLE OR RENEWABLE. A visa issued on arrival can be extended only in extraordinary circumstances such as natural disasters, accident, or illness. If you want to stay in Indonesia longer than the 30 days you must exit and re-enter the country on a new tourist visa.

Visa purchasing takes 15-30 minutes per applicant, depending on the number of persons applying. Payment counters, a bank counter, and a money changer have been set up to process payments. Passport must be valid for at least six months from the date of arrival. Payment must be made on arrival. An onward or return trip ticket must be shown on arrival.

II. Visa free facility

Visa free facility is granted to the citizens of 11 countries whose governments extend visa free facility to Indonesian nationals would continue to enjoy short visa-free stays. Included in the 11 countries and administrative districts that are granted the 30-day vis-free facility are: Brunei Darussalam, Chile, Hong Kong Special Administrative Region, Macau Special Administrative Region, Malaysia, Morocco, Peru, The Philippines, Singapore, Thailand, and Vietnam.

Visitors with the visa-free facility will be able to proceed directly to the immigration clearance counter after deplaning. Passport must be valid for a minimum of six months from the date of arrival. Onward or return tickets must be shown on arrival.

III. Citizens of other countries

Citizens of other countries not on the visa on arrival or visa free lists will be required to apply for a visa overseas (in their home country) before entering Indonesia. Citizens of any country wishing to stay more than 30 days must also apply for an appropriate visa (cultural visit or business) at their nearest Indonesian Embassy of Consulate before travelling to Indonesia.

Tour agents are able to arrange express handling for groups at no additional charge by presenting the completed immigration cards, passports and applicable visa fee. Passengers who overstay their visa period for a short period of time can be processed immediately at the airport by paying $20 every day they overstayed their 30-day visa. Airlines that experienced technical difficulties or delayed flights can apply for their passengers to be exempted from paying any overstay penalties.

Source : Ministry of Culture and Tourism, Republic of Indonesia