CISA has published a recommend list  of Free Cybersecurity Services and Tools.  These are valuable resources for security ADMINs to learn/use in defense of their corporate networks

CISA Compiles Free Cybersecurity Services and Tools for Network Defenders | CISA

Free Cybersecurity Services and Tools | CISA

CISA has compiled and published a list of free cybersecurity services and tools to help organizations reduce cybersecurity risk and strengthen resiliency. This non-exhaustive living repository includes services provided by CISA, widely used open source tools, and free tools and services offered by private and public sector organizations across the cybersecurity community. Before turning to the free offerings, CISA strongly recommends organizations take certain foundational measures to implement a strong cybersecurity program:

CISA encourages network defenders to take the measures above and consult the list of free cybersecurity services and tools to reduce the likelihood of a damaging cyber incident, detect malicious activity, respond to confirmed incidents, and strengthen resilience.