ESI Audiotechnik GmbH is a German audio equipment manufacturer headquartered in Leonberg, Baden-Württemberg. The company traces its origins to RIDI multimedia GmbH, founded in 1998 by Claus Riethmüller, and inherited the ESI brand name from the Korean audio products company Ego Systems, Inc. ESI Audiotechnik GmbH was formally established in 2006, and by 2010 all product design and development had moved to the German headquarters.

ESI produces a wide range of studio-oriented audio gear, including USB audio interfaces (the Amber i1, Amber i2, Amber i4, Neva Uno, Neva Duo, MAYA22 USB, MAYA44 USB+, U22 XT, U24 XL), PCIe audio interfaces (Juli@ eX, MAYA44 eX), Dante-based network audio interfaces (planet 22c, planet 22x), MIDI interfaces (M4U eX, M8U eX, MIDIMATE eX), and active studio monitors (the nEar and uniK series). The company is also known for its Xkey line of slim MIDI keyboard controllers, available in 25- and 37-key versions with wireless Bluetooth variants (Xkey Air). ESI was among the first manufacturers to offer compact 5-inch active monitors aimed at home studios and helped popularize the use of Kevlar cone drivers in affordable studio monitors.

ESI occupies a niche in the budget-to-midrange segment of the pro audio market, designing products in Germany that cater to home studio owners, bedroom producers, and semi-professional musicians seeking reliable audio hardware without a premium price tag.

ESI has 23 products cataloged on Equipboard, including Audio Interfaces, Active & Passive Monitors, and MIDI Interfaces. Their gear is featured by 6 artists, with the strongest followings in Electronic and Rock. Notable users include Rodney Orpheus, Chymera, and JayB.