A collection of useful resources and tools:

LinkDescriptionLicence
CyberChefThe Cyber Swiss Army Knife for encryption, encoding, compression and data analysisOpen source
SignalPrivacy focused end to end encrypted messaging applicaitonOpen source
VirtualBoxHosted hypervisor to manage guest virtual machinesOpen source
Kali trainingLearn about the Kali Linux distributionFree
NMapNetwork mapper tool for network discovery and security auditingOpen source
LynisOpen source security auditing tool for LinuxOpen source
Parrot OSProfessional tools for security testing, software development and privacy defense, all in one place.Open source
Regex101Test and debug regular expressionsFree