Reposify is described as 'attack surface management platform delivering autonomous, 24/7 discovery of internet exposed assets across all environments and the supply chain'. There are five alternatives to Reposify for Online / Web-based, Android, Mac, Windows and Linux. The best alternative is Shodan, which is free. Other great apps like Reposify are Censys (Freemium, Open Source), ZoomEye (Freemium), BinaryEdge (Freemium) and Grabber Web Application Scanner (Free, Open Source).
Shodan is a search engine that lets you find specific computers (routers, servers, etc.) using a variety of filters. Some have also described it as a public port scan directory or a search engine of banners.
Grabber is a web application scanner. Basically it detects some kind of vulnerabilities in your website. Grabber is simple, not fast, but portable and really adaptable. This software is designed to scan small websites such as personal sites, forums etc.