Cryptographic keys are a fundamental aspect of modern system security, but when compromised, they become a critical vulnerability, especially in ransomware attacks. Paradoxically, these keys must be available in memory at runtime to function, creating a unique opportunity for defensive tools. We introduce KeyReaper, an open-source tool designed to locate cryptographic keys in active Windows processes using advanced memory analysis. Unlike traditional approaches that rely on static memory dumps, KeyReaper performs dynamic analysis in real time, restricting the search to process heap memory to improve efficiency and accuracy. It employs robust key identification heuristics to minimize false positives and is designed for seamless integration with Endpoint Detection and Response systems. KeyReaper also encourages extensibility: its open-source nature allows researchers and practitioners to enhance its capabilities with custom key detection algorithms. We validated our approach through extensive experiments involving both proof-of-concept ransomware and real-world samples, demonstrating the effectiveness of key extraction and decryption success. Our tool provides a practical path to strengthening ransomware mitigation strategies.