The top two most powerfull bombs are with the Russians and United States of America
1. MOAB or the The GBU-43/B Massive Ordnance Air Blast bomb (nicknamed Mother Of All Bombs) is developed for the United States military.
Weighing in at 21,000 pounds, the MOAB is packed with some 18,000 pounds of a gelled slurry of ammonium nitrate and powdered aluminum that is detonated by a highly explosive booster.
It is satellite guided. It was successfully field test at Eglin Air Force Base, Florida on March 11, 2003
2. Aviation Thermobaric Bomb or Vaccum bomb (nicknamed Father Of All Bombs) is reportedly four times more powerful than the U.S. military's GBU-43/B Massive Ordnance Air Blast bomb. This was developed by the Russian Air Force.
It was successfully field-tested in the late evening of September 11, 2007.
Heres a News report from Russian Media "Russia Today" during the Vaccum bomb test in Russia.