Yes, it is safe to boil Mason jars. It is a common method to
sterilize glass jars
. There are a few things that you need to take care of:
Do not boil frozen canning jars. Thermal shock can cause breakage.
Do not use vintage Mason jars.
Do not pour boiling water into Mason jars if the jar is cold.
It is safer to place your glass jar in a
boiling water Canner
and allow it to boil along with the water. The gradual temperature change will ensure the safety of your glass jar.
Do not boil Mason jar seals and metal rings. Boiling it will ruin the rubber gasket on the inside of the lid, which will prevent you from vacuum-sealing the jars.