Citizens of many countries will not need a visa to travel to Singapore and will be allowed to stay up to 2-4 weeks.
However, if in doubt, please check with the embassies in your country (you can find the Singapore embassy in your country here or you can check visa requirements on www.ica.gov.sg and follow the “Check if You Need Entry Visa” link (under Visitors)). Please make sure that for travel to Singapore your passport is valid for at least another 6 months from the time of arrival.