In this work, linear and nonlinear optical properties of electro-/acido-/photo-switchable indolino[2,1-b]oxazolidine derivatives were investigated. The linear optical properties of the closed and open forms have been characterized by UV-Visible and IR spectroscopies associated with DFT calculations. Nonlinear optical properties of the compounds have been obtained by ex-situ and in-situ hyper-Rayleigh experiments in solution. We show that protonated, oxidized and irradiated open forms exhibit the same visible absorption and NLO features. In particular, the closed and open forms exhibit a huge contrast of the first hyperpolarizability with an enhancement factor of 40-45. Additionally, we have designed an original electrochemical cell that allows to monitor in-situ the hyper-Rayleigh response upon electrical stimulus. We report notably a partial but good and reversible NLO contrast in-situ during oxidation/reduction cycles. Thereby, indolinooxazolidine moieties are versatile trimodal switchable units which are very promising for applications in devices.