Was the Nazi party in world war 1?

No, The Nazi Party didn't exist until 1919, the year after the war, and didn't grow in popularity until 1925.

Hitler did serve as a messenger in ww1 in a Bavarian regiment earning 1 or 2 medals. He was sent to spy on the Nazi Party to begin with in the early days but then found he belived what they were saying so he joined them. A lot of historians belive the 1st world war affected Hitlers views on the world.