Most current sit-to-stand devices are electrically powered. These devices, typically chairs, are for home use and are not portable. Yet there is a great need for a device that can be used anywhere. This paper proposes a novel portable device, named the QuickStand. Its working principle is based on a spring which provides partial support. When sitting down, this spring stores energy, which becomes available in getting up. A lock avoids undesired release of spring energy. The device is adjustable to subjects and chairs, making it very versatile. A prototype was manufactured. Technical evaluation showed the ability to provide around 150 N of support force over the whole range of motion. The device was successfully tested on a subject with a full body muscle disorder.