Simon Kaplan is a United States-based French composer, music theorist and instructor. His oeuvre, published by BabelScores, encompasses a diverse range of solo, chamber and electronic pieces premiered by esteemed performers across Belgium, Denmark, France, Japan and the United States. From 2017 to 2018, he was the composer and orchestrator of the Great Synagogue of Europe. Presently, he serves at the University of North Texas as a teaching assistant and fellow.

In 2021, the then-young artist invented diahemitonicism, a pioneering quarter-tonal composition system which has become a defining feature of his musical style. In 2024, he developed the kaplanophone, a quarter-tonal virtual keyboard instrument with an inharmonic timbre playable via a pair of MIDI controllers equipped with two pedals. In 2025, he devised a set of nine temperaments for the quarter-tone scale: one Kaplanian, six meansemitone and two circular ones designated Kaplan I and II.

The microtonalist has lectured on his innovations at venues such as the Royal Flemish Conservatoire of Brussels, Aristotle University of Thessaloniki, Regional Conservatoire of Lille, Departmental Conservatoire of the Choletais and Mozarteum University of Salzburg. His articles have been published in Tempo and Xenharmonikon.

Kaplan earned his Master of Arts in Composition from the Royal Flemish Conservatoire of Brussels in 2022, where he studied under Peter Swinnen. He furthered his academic pursuits in Claude Ledoux's class at the Royal Conservatoire of Mons, graduating with a Master of Music in Compositional Didactics in 2023. He also benefited from the teaching of Alan Belkin, Henry Fourès, Dimitri Papageorgiou and Calliope Tsoupaki through private lessons and masterclasses. Currently, he is pursuing doctoral studies at the University of North Texas under the guidance of Andrew Chung, Sungji Hong, Panayiotis Kokoras, Jon Nelson and Kirsten Soriano. He expects to receive his Doctor of Philosophy in Composition with a Minor in Music Theory in 2027.