Show HN: HeimWall – Catch secrets before you paste them into Claude or Cursor (heimwall.ai)

HeimWall, a new free menu-bar app for Mac, aims to protect developers by flagging sensitive information or personally identifiable information (PII) before it gets pasted into AI tools like Cursor, Claude Code, and Copilot. The app operates entirely offline, ensuring that no data is sent or stored externally. By employing deterministic regex and a small on-device classifier, HeimWall quickly scans prompts in real-time, alerting users in under 50 milliseconds if any secrets—such as AWS keys or credit card numbers—are at risk of being inadvertently shared. This app is significant for the AI/ML community as it addresses a critical security concern: the accidental exposure of sensitive data when using AI coding assistants. With over 25 predefined rules to detect common credentials, HeimWall provides a robust safeguard against mishaps that could lead to data leaks or security breaches. Its design emphasizes user privacy by eliminating the need for accounts or cloud integration, making it an appealing choice for developers concerned about data security in their workflow. As AI tools become increasingly integrated into software development, solutions like HeimWall play a vital role in maintaining user trust and data integrity.