The Keuffel and Esser Co., also known as K&E, was an American drafting instrument and supplies company founded in 1867 by German immigrants Wilhelm J. D. Keuffel and Hermann Esser. It was the first U.S. company to specialize in these products.

Keuffel and Esser was acquired by AZON Corp. in 1987.

Keuffel and Esser started in New York, selling drawing materials and drafting supplies. In 1876, K&E started selling surveying instruments. The four-story Keuffel and Esser Manufacturing Complex in Hoboken, New Jersey, was completed four years later. K&E was incorporated in 1889.

From 1889 until World War II, K&E employed "Spider Lady" Mary Pfeiffer to manage a "spider ranch" for the firm. It produced strands of spider web used in making crosshairs for telescopic sights.

In 1892, the company commissioned the architecture firm of De Lomos & Cordes to build a showroom and offices at 127 Fulton Street in Manhattan. The firm designed an eight-story brick and terracotta building in the Renaissance Revival style. The building was completed in 1893, and the company occupied it until 1961. It was designated a New York City landmark in 2005.

In the first decade of the 20th century, Keuffel and Esser introduced a new line of surveying instruments based on the work of John Paoli, an Italian immigrant in Hoboken. A new Keuffel and Esser Manufacturing Complex was built in 1906, after the previous building was destroyed by fire. The building was converted to housing in 1975 and was added to the National Register of Historic Places on September 12, 1985.

K&E acquired instrument maker Young & Sons of Philadelphia in 1918 and made it a department of the firm, retaining the brand name for a time.

The Leroy K&E Controlled Lettering System uses a pantograph for mechanical technical lettering.