A short reminder/guide to the Indonesian public holidays:

1 January Tahun Baru Masehi (New Year's Day)
21 April Hari Kartini (Women Emancipation Day)
22 April Hari Bumi (Earth Day)
1 May Hari Buruh (Labor Day)
2 May Hari Pendidikan Nasional (National Education Day)
20 May Hari Kebangkitan Nasional (commemorating the 1908 formation of Boedi Oetomo)
22 May Hari Reformasi (Reformation Commemoration Day)
1 June Hari Lahir Pancasila (commemorating Sukarno's 1945 address on the Pancasila ideology)
23 July Hari Anak Nasional (National Children Day)
17 August Hari Kemerdekaan (Independence Day)
1 October Hari Kesaktian Pancasila (the day after 30 September Movement)
2 October Hari Batik (National Batik Day)
5 October Hari Tentara Nasional Indonesia (Armed Forces Day)
28 October Hari Sumpah Pemuda (commemorating the 1928 Youth Pledge)
10 November Hari Pahlawan (commemorating the 1946 Battle of Surabaya)
22 December Hari Ibu (Mother's Day)
25 December Hari Natal (Christmas Day)

The Gregorian dates for the following Indonesian public holidays vary each year:

Maulid Nabi Muhammad Birth of Prophet Muhammad
Tahun Baru Imlek Chinese New Year
Hari Raya Nyepi Hindu/Balinese New Year
Wafat Yesus Kristus Good Friday
Waisak Birth of the Buddha
Isra Mi'raj Nabi Muhammad Isra Mi'raj (Ascension of Prophet Muhammad)
Kenaikan Yesus Kristus Ascension Day
Idul Fitri Eid al-Fitr (the day after Ramadhan)
Idul Adha Eid al-Adha (the qurban/sacrifice day)
Tahun Baru Hijriah Islamic New Year