<p>TotPrePart is an innovative online tool for partitioning of daily total precipitation into its two main phases, snowfall and rainfall. Precipitation is converted into its two main phases, rain and snow, by combining total precipitation and air temperature timeseries with conversion coefficients to allow for calculation of snowfall amount (mm and cm) and rainfall amount (mm). The tool’s streamlined interface integrates a test data set, as well as customizable calibration, visualization and data export routines. TotPrePart has been developed in an effort to promote open science, and hence it is freely available (<a href="https://totprepart.hydrotools.tech">https://totprepart.hydrotools.tech</a>) and can be used for any location for which the required input data (i.e., daily total precipitation and air temperature) is available. In this paper, the conceptual model and online interface, as well as an example of TotPrePart application using data collected during a 12-year (2008–2019) field study conducted at the Agriculture and Agri-Food Canada Harrington Experimental Farm (HEF) in Prince Edward Island (PEI), Canada are presented. Statistical indicators indicated an excellent performance of the tool (i.e., R² &gt; 0.5, NRMSE &lt; 50% and − 25%&lt; PBIAS &lt; 25%) when the output was compared to weather station data for both calibration and validation datasets. TotPrePart fills an existing gap relative to the availability of online and offline precipitation phase partitioning tools due to its ease-of-use, robustness and flexibility, and shows promise to be adopted as an alternative for more complex, standalone models, that might require extensive resources and expertise.</p>