Noodler's Ink is a brand of fountain pen ink developed by pen collector Nathan Tardif. Noodler's is known for offering inks in a wide variety of colors and characteristics. Of particular note are the "bulletproof" inks. These react with cellulose in paper to form waterproof and UV-resistant marks. Noodler's Inks also offers inks with very low freezing points, fluorescent inks for use in highlighting, inks containing lubricants for certain pen mechanisms, and invisible inks.