I hate to be snarky, but if DAVID is down then that's good for everyone.

DAVID hasn't updated their Gene Ontology annotations in over five years:

Google Scholar says 2121 pubs cited DAVID in 2014, when annotations were 5 yrs old #ugh #bioinformatics #geneontology pic.twitter.com/P2VYMIOv9u

— Andrew Su (@andrewsu) April 28, 2015

Lots of gene annotations have been added (and some deleted) in those years. Despite many pleas from the biocuration community over many years, the maintainers of DAVID are either unwilling or unable to make these updates. So unless you want your analyses to be based on five year old knowledge, find another enrichment tool. (I suggest Panther http://pantherdb.org/ because it is developed by one of the Gene Ontology PIs.)

Take the oath! Thou shalt not use DAVID!

Until it comes back up, you might try iPathwayGuide as an alternative. We offer an easy to use web application that is 100% free to use for doing pathway analysis among other analyses. You can watch a short overview video about the application below.

In past 2 months at least for me it was going up and down. However, the problem was that even when it was up, I was never able to see it loading the functional annotation results page. It would be very sad if this great web resource is not maintained anymore..

How about considering real-time update tool like GeneSCF,

Gene Set Clustering based on Functional annotation (GeneSCF)