Ways to keep a mac from sleeping with the lid closed

Hello all. I have a macbook air. I have been doing some reading on ways to keep the macbook from sleeping with the lid closed. From what I see Apple does not allow this and you need to use a 3rd party app. Other then internet sharing which I am not so sure about. I would like to be able to close the lid due to things like having cats who like to dance on the keyboard. Has anyone tried any of the 3rd party apps? If us what worked well? Is there any other way to do this that you know of? Thanks for any help.