Mario Builder is made by TheTingThing, over at YoYo Games Forums. As far as I know, this is Windows only. (If Mac users manage to play this on their Mac, let me know). You can download it here.

However, there is a major flaw. As far as I know with this, you cannot share your games over the internet. Someone must be with you to play your game.

When building your level/world maps, use CTRL to place tiles down rapidly, and the right click button on your mouse to delete things. When editting your world map, and you use more than a 1x1 grid, use W to move your map up, S to move your map down, A to move your map left, and D to move your map right.

Leave your thoughts here. Much appreciated!

Also one final note: if you can, give us screenshots of your maps, and maybe some videos if you can!

Super Mario Bros. X; A maker that was recently discontinued, but can be found in google. It's the best downloadable Mario Maker made.

but lol dark, it is an ok maker. Super Mario Bros. X

The fact that you can't share your levels is kind of a downer. In that sense, Super Mario Bros. X is kind of superior. It's a shame that redigit discontinued the project, however.