The rate of aging is a complex indicator of human health which depends on many factors that include external and internal effects on the body (disease and its correction processes), which is reflected in the biomedical indicators of the body (functional, biochemical, hematological and others). To determine the rate of aging, the concept of bio-age is widely used, which is a complex parameter based on ascertaining the degree of human body aging (wear, damage) in reliance on its biomedical parameters. This article presents the development of a client-server web-application for determining the bio-age of a user by evaluating their functional indicators - systolic blood pressure, diastolic blood pressure, breathing delay time on inhalation, breathing delay time on exhalation, the value of lungs vital capacity, hearing acuity, the state of eye lens accommodation, static balancing time, body weight, height. The web-application allows doctors and administrators to determine the patient-#039;s bio-age, drawing on the user-#039;s functional data entered in the application, taking into account the influence of geroprophylactic therapy. The web-application displays data in the form of a list and a graph and enables one to send reports to the patient-#039;s email and to upload them. The server part of the application is written in the C# programming language and ASP.NET framework. The TypeScript programming language and the React framework with the Antd user interface component library were employed to design the client part of the application. PostgresSQL is utilized as a database. As a module for predicting biological age, a previously developed mathematical model, trained on a data sample of 650 records and having an accuracy of 5.87 years, is applied. The ability to predict the patient-#039;s bio-age with consideration to the duration and a type of geoprophylactic exposure makes the developed application a suitable tool to identify the leading mechanism of a patient’s aging.