No visa is required by nationals of most countries although they may be somewhat strict in enforcing that you have a return/onward ticket and sufficient funds for your stay.

Nationals from Afghanistan, Bangladesh, Indonesia, Iraq, Iran, Laos, North Korea, Libya Mali,  Pakistan, Palestine, Philippines, Sahrawi Republic, Somalia, Sri Lanka, Sudan, South Sudan, Syria, Taiwan, Viertnam and Yemen must have a visa prior to arrival.

Everyone else either needs no visa or can buy a visa on arrival at the airport.

Mauritius - Visa Information

Mauritius embassies