For security reasons, private housing estates and offices need to change their access password regularly. Many residential estates and commercial offices have adopted Octopus as a security access system, providing added convenience for over 100,000 residents and employees.

As each Octopus has a unique ID number, cardholders only need to register their Octopus at the management office, and the ID will be stored in the central security system. Authorised holders simply hold their Octopus over the reader at the door/gate to enter the building. They no longer need to memorise any access code or carry another access card. Octopus holders who are not residents or employees will not be able to gain access to the building.