None of the strong acids traditionally listed in a chemistry text holds the title of the world’s Strongest Acid. It used to be Fluorosulfuric Acid HFSO3, but the Caborane are millions of times stronger than the HFSO3, and also is more powerful than concentrated sulfuric acid.
The carborane acids are also incredible proton donors, but they are not corrosive. Corrosiveness is related to negatively-charged part of the acid. Hydrofluoric acid HF, it’s an example of a corrosive because it dissolves glass. But it’s not considered to be strong acid because it does not completely dissociate in water.
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