President Obama has not officially pardoned Hillary Clinton for any crimes.
There is no question that the Constitution’s broad pardon power permits you to pardon someone who has not been convicted, or even charged, with a crime. The most famous pardon of all, President Ford’s pardon of Richard Nixon, a month after Gerald Ford took office. It occurred in the absence of any indictment. It has been the law since at least 1867 that the President may pardon someone anytime after the offense is committed.
Obama has pardoned or commuted the sentences of more than 1,000 people — becoming the most forgiving president in history.