Real estate company seeks software for internal building management

We are looking for internal building management software for our real estate company, i.e., internal real estate management (without brokerage functions or similar). IMPORTANT: We are not looking for “built-in” software with selection tabs, but rather a customizable solution. We would like to be able to create “activities” that can have different functions (appointments, internal messages, telephone notes, incoming and outgoing emails). This would allow for universal use. Master data, etc., can be entered via a fixed interface, but the operation of everyday tasks should be intuitive and freely configurable.

We have the following requirements for the software:

• Creation of buildings, contact persons, companies, etc.
• Storage of documents (maintenance logs, reports, etc.) with link function
• Calendar function with reminder function for recurring appointments
• Internal and external communication (via email externally, and within the program for internal communication)
• Clarity and a comprehensible structure are important; colorful graphics, etc., are not necessary.
• Since part of our building stock is also rented out, there should be some possibility of rental management.
• Windows-compatible

Initially, approximately five workstations are required, with the possibility of expanding to 10-15 workstations in the long term.