This discloses a knot untier. The knot untier consists of an arm or pawl which is inserted into the knot to be untied plus, in some embodiments, a base which resembles a credit card. The knot untier in one embodiment is thus small enough to fit in a wallet. The knot untier may also be hung on a keychain. The knot untier does not, as many existing untiers do, damage most lines.