The diagnosis and monitoring of Alzheimer's Disease (AD), which is the most common form of dementia, has been the motivation for the development of several screening tests such as Mini-Mental State Examination (MMSE), AD Assessment Scale (ADAS-Cog), and others. This work aims to develop an automatic web-based tool that may help patients and therapists to perform screening tests. The tool was implemented by adapting an existing platform for aphasia treatment, known as Virtual Therapist for Aphasia Treatment (VITHEA). The tool includes the type of speech-related exercises one can find in the most common screening tests, totalling over 180 stimuli, as well as the Animal Naming test. Its great flexibility allows for the creation of different exercises of the same type (repetition, calculation, naming, orientation, evocation, ...). The tool was evaluated with both healthy subjects and others diagnosed with cognitive impairment, using a representative subset of exercises, with satisfactory results.