OUAPI is described as 'is the inventory manager for your small company (computer, software, printers' and is an app. There are four alternatives to OUAPI for a variety of platforms, including Self-Hosted solutions, Linux, Online / Web-based, Windows and Mac. The best alternative is GLPI. It's not free, so if you're looking for a free alternative, you could try Ralph or Simple It Helpdesk.
GLPI is an IT Service Management software based on open source technologies. It is a suite for IT, project, financial and user management. GLPI can support companies of any size, and offers both on-premises and cloud (SaaS) solutions.