THURBO, a joint venture of Swiss Federal Railways and the canton of Thurgau, operates the service.

The S9 operates every 30 minutes between Wil and Wattwil, using the Wil–Ebnat-Kappel line.

[3] The route follows the left bank of the River Thur through the lower Toggenburg Valley.

S9 Wil SG – Wattwil Until the December 2013 timetable change, every other S9 service continued south to Nesslau-Neu St. Johann, providing hourly service to the remainder of the Wil–Ebnat-Kappel line and the short section of the Bodensee–Toggenburg line between Nesslau-Neu St. Johann and Ebnat-Kappel.

With the timetable change, the S9 was cut back to its present terminus and the former S8 (which later merged with the former S1) extended to Nesslau-Neu St.