What's your favorite free/open source tools that have helped you in your job?

For example, I use Sandboxie-plus for reviewing phishing email links and determining the legitimacy of an email. OWASP Zap as well for web app vulnerability analysis. Also use SpiderFoot for OSINT analysis, trying to talk the boss into getting the enterprise version. OTX Alienvault has been awesome for threat hunting. [SecurityScoreboard.io](https://SecurityScoreboard.io) for getting external vulnerability analysis.

What say you?

cybersecurity free job open source open source tools tools