OLL 41
The algorithm, how to recognise it and how to practise it without cheating.
Recommended algorithm
R U R' U R U2 R' F R U R' U' F'13 moves
How to recognise it
Yellow on top: the back and left edges and the two front corners. The back corners' yellow faces back, like headlights.
Its inverse is another case
Do the 41 algorithm backwards, F U R U' R' F' R U2 R' U' R U' R', and you are solving 43.
That's why CubeDojo never scrambles 41 that way: it builds a random state with the case fixed, so you practise 41 and not 43.
Practise 41 now
Random-state scrambles, a timer and spaced review. Free, on the web and on your phone.