High-entropy alloys are attractive as brazing materials that usually exhibit significantly higher yield strength and ductility. Heat resistance of brazed joints is limited by the content of the eutectic phase that is typically used in the filler metals to decrease brazing temperature. Designing and applying high-entropy filler metals for joining superalloys, refractory metals, carbon-fiber composites can resolve many technical problems in the manufacture of new power sources, jet and rocket engines, high-temperature electronic devices, etc. We present new Ti4Zr1Nb1Cu1.5Ni1.5, Co3Ni1Si1Mo1Cr1.3 and Co3Ni1Si1Nb1Cr1.3 high-entropy alloys having relatively low brazing temperature in the range of 1050-1200°C but exhibiting high heat resistance in the service temperature range of 600-800°C. Shear strength of Ti-6Al-4V alloy, as well as of Molybdenum, was tested at 600°C and 800°C. Microstructure of brazed joints was studied by optical and scanning electron microscopy. Application in vacuum brazing, effect of the post-braze diffusion treatment, and future developments are also discussed.