<p>In recent years, the identification of fluid density and viscosity has gained substantial significance across a wide range of industries and scientific fields. These parameters are of utmost importance in comprehending fluid behaviors as accurate measurement of these properties is essential for quality control, process optimization, and product development. A variety of traditional approaches, including capillary, falling ball, volumetry, isochoric, hydrostatic weighing, buoyancy methods, etc., are employed to measure viscosity and density. These traditional approaches require a large amount of samples for measurement and are time consuming. Many modern approaches with different sensing principles have been introduced to overcome the drawbacks of traditional methods. This paper comprehensively describes the densitometers, and viscometers on the basis of different sensing principles such as cantilever, acoustic, tuning fork, diaphragm, pressure, magnetic field, etc. Furthermore, specifications of viscometers and densitometers are briefly summarized, which include the working mechanism, sample range, sample volume, resolution/sensitivity, accuracy/error, testing sample, and temperature. Through this, a mass insight into viscosity and density measurements can be found for wide range of liquids/gas across diverse applications including biopharmaceuticals, protein therapeutics, lubricants, adhesives, healthcare, food production, cosmetics, construction, paints, as well as fuel and petroleum.</p>