30 seconds on Google:
"The democratic system in India is based on the principle of universal adult suffrage; that any citizen over the age of 18 can vote in an election".
In the USA, "Since 1996, a federal law has prohibited non-citizens from voting in federal elections, punishing them by fines, imprisonment, inadmissibility".
"To vote in a Canadian federal election you must be: A Canadian citizen (Temporary and permanent residents cannot vote); 18 years old or older on election day".
Jamaica seems to be about the only commonwealth country that allows non-citizens to vote. They permit a vote to commonwealth citizens who have been resident for the preceding 12 months.