Kingfisher, an open-source secret scanning tool developed by MongoDB, addresses the challenges of credential-related security risks by detecting and verifying exposed secrets across code repositories and file systems. Unlike traditional secret scanners, Kingfisher not only identifies potential secrets but also validates them against external systems to determine their activity status, thus reducing false positives and focusing on real threats. Built in Rust for performance and safety, it integrates seamlessly into CI/CD pipelines and supports multiple cloud platforms, maintaining high-speed scanning and real-time validation without sensitive data leaving the user's infrastructure. Kingfisher plays a pivotal role in MongoDB's internal security strategy, enhancing the detection and management of secrets while contributing to higher Supply-chain Levels for Software Artifacts (SLSA) compliance. Now released to the broader community, Kingfisher empowers developers and security teams with a robust tool that helps protect critical assets and embodies MongoDB's commitment to open-source solutions.