In order to maintain the effects achieved during the psychosomatic rehabilitation, according aftercare is indicated for most rehabilitation patients. Due to the current low supply of aftercare psychotherapists (so-called aftercare therapists) licensed by the German Pension Insurance web-based aftercare provides an equivalent alternative to analogue (in person) offers. This study clarifies which characteristics indicate that web-based aftercare is particularly recommended and how web-based formats are evaluated by participants, especially with regard to the therapeutic relationship. 142 psychosomatic rehabilitation patients were randomly assigned to analogue aftercare or web-based aftercare if a service close to their home was available (equivalence study design). Test variables were collected by questionnaires and analyzed stratified for age and gender. For male participants, there are no significant differences between the two aftercare formats. Women appear to have lower long-term depression scores when participating in web-based aftercare. Participants till the age 50 benefit significantly more from web-based aftercare than rehabilitants above age 50, The quality of the therapeutic relationship is rated equally well in both aftercare formats. Particularly in view of the increasing digitization of healthcare in times of the corona pandemic, web-based aftercare services offer the possibility of providing patients with aftercare independent of the availability of analogue-services and with the same benefits as analog therapies. Demographic factors such as age and sex must be taken into account when determining the indication. Therapists should recommend web-based aftercare especially for younger patients and for women, while men and older patients can be recommended both services equally. Therapists who offer web-based aftercare should be trained in advance on technical and content-related aspects, as was done in the present work.