What is the time complexity of the permute method, which generates all permutations of an array?

public void permute(int[] arr, int start) {
    if(start == arr.length) {
        System.out.println(Arrays.toString(arr));
        return;
    }
    for(int i = start; i < arr.length; i++) {
        swap(arr, start, i);
        permute(arr, start + 1);
        swap(arr, start, i);
    }
}

// Assume swap() correctly swaps two elements in the array.