Hallie is the diminutive of Harriet (English, "home ruler") and also potentially of Hallel or Halleli (Hebrew, "praise") or of Haley (Old English, "hay meadow").
Hallie has been rising in the U.S. Today it sits in the U.S. top 500.
Hallie does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Hallie reduce to 2, The Peacemaker. This is a traditional interpretive system, not a factual claim about the name.