Sublist3r is a subdomain enumeration tool and passive reconnaissance framework designed to discover subdomains by querying search engines and public intelligence sources. It functions as a security tool for identifying the digital footprint of a target domain. The project provides both passive enumeration through multi-source API aggregation and active discovery via a DNS brute force tool. It includes a TCP port scanner to identify active services and open ports on discovered subdomains, facilitating attack surface mapping. The tool can be used as a standalone utility or as a Python security