Time Travelers affected the outcome of World War II

Consider this a discussion prompt, because obviously we have no direct evidence of time travel, or that it affected the outcome of World War II.

However, I've been thinking for awhile about the realities of WWII.

The Nazis had a massive technological edge on every other nation. They had submarines, jet aircraft, rockets, a nuclear program, coal gasification plants and mechanical computers before anybody else.

If you told me a country with that technological edge would lose the war, it would be hard to believe.

So, speculate time travel friends. How would time travelers have intervened to prevent a Nazi victory in WWII?