I wanted to be sure before I spoke. Our local “Winco” super market, which is the low cost, bag your own, we don’t take credit cards, nothing fancy here, grocery store carries it which means it’s probably pretty ubiquitous in grocery stores in the US. I think I’ve seen it in our local corner “If you really need it we probably have it” hardware store too.
Oxalic acid’s main applications include cleaning or bleaching, especially for the removal of rust (iron complexing agent), e.g. Bar Keepers Friend is an example of a household cleaner containing oxalic acid. Its utility in rust removal agents is due to its forming a stable, water soluble salt with ferric iron, ferrioxalate ion.
I just know you all were wanting to know this 🙂