Most western nationalities do not require a visa, you will get issued 14 or 30 days on arrival.
Nationals from: Afghanistan, Algeria, Bangladesh, China, Commonwealth of Independent States, Egypt, Georgia, India, Iran, Iraq, Jordan, Lebanon, Libya, Mali, Morocco, Myanmar, Nigeria, North Korea, Pakistan, Palestine, Saudi Arabia, Somalia, Sudan, Syria, Tunisia, Turkmenistan, Ukraine and Yemen will need to organise a visa in advance.
Singapore has a working holiday agreement with students from Australia, France, Germany, Hong Kong, Japan, New Zealand, Switzerland, United Kingdom and the United States.
Visa requirements Singapore
Foreign embassies in Singapore
Singapore working holiday information