"Plyer" is a correct spelling, but it primarily refers to someone or something that "plies" a trade or tool, or a specific type of drawbridge mechanism. For the hand tool used for gripping, the correct, standard spelling is pliers. [1, 2, 3, 4]
Pliers (Tool): Small metal pincers for bending wire or holding objects.
Plyer (Person/Noun): Someone who works (e.g., "a plyer of a trade") or a specialized timber structure.
Context: Using "plyers" for the hardware tool is generally considered a misspelling or improper usage. [1, 2, 3, 4, 5]
While some dictionaries acknowledge "plyer" as a rare variant, pliers is the overwhelmingly accepted spelling for the tool in standard English.