Over three decays have passed since the first discovery of high temperature superconductor (HTS) back in 1986. Despite the early expectation on strong potential of HTS on various industries, its application has been quite limited to laboratory research magnets until the early 2010s, mainly due to the well-known technical challenge of “quench protection” of high-performance HTS magnets. In 2009, the so-called no-insulation (NI) HTS winding technique was reported for the first time by MIT, which provides a new feasible philosopy to protect HTS magnets. The key idea of the NI technique is to allow current sharing among adjacent turns upon a quench, which essentially enables the “electric-burn-out-free” operation even at an extremely high operating current density of >1000 A/mm2. Nowadays, it is applied to various applications beyond high field laboratory magnets, which include fusion, accelerator, wind turbine, electric propulsion, MRI/NMR, energy storage and more. This seminar presents a summary of the recent progress on the NI HTS magnet technology and some selected applications with a focus on nuclear industries. Also key challenges and potential solutions for the next-generation high field HTS magnets and their applications are also discussed, if not limited to NI.