Jost Bürgi (also Joost, Jobst; Latinized surname Burgius or Byrgius; 28 February 1552 – 31 January 1632[1]), active primarily at the courts in Kassel and Prague, was a Swiss clockmaker, mathematician, and writer.

Bürgi was born in 1552 Lichtensteig, Toggenburg, at the time a subject territory of the Abbey of St. Gall (now part of the canton of St. Gallen, Switzerland).

Not much is known about his life or education before his employment as astronomer and clockmaker at the court of William IV in Kassel in 1579; it has been theorized that he acquired his mathematical knowledge at Strasbourg, among others from Swiss mathematician Conrad Dasypodius, but there are no facts to support this.

[2] Another autodidact, Nicolaus Reimers, in 1587 translated Copernicus' De Revolutionibus Orbium Coelestium into German for Bürgi.

An introduction to some of Bürgi's methods survives in a copy by Kepler; it discusses the basics of Algebra (or Coss as it was known at the time), and of decimal fractions.

[8] It is undocumented where he learned his clockmaking skills, but eventually he became the most innovative clock and scientific instrument maker of his time.

[11] Working as an instrument maker for the court of William IV, Landgrave of Hesse-Kassel in Kassel[12] he played a pivotal role in developing the first astronomical charts.

From then on Bürgi commuted between Kassel and Prague, and finally entered the service of the emperor in 1604 to work for the imperial astronomer Johannes Kepler.