I use 1Password password manager for saving all my passwords, various other credentials and private notes and it has been a lifesaver thus far. Having a unique password for all my accounts and using 2FA wherever available means I should be quite safe in case any of my accounts gets breached or the password gets leaked.
Lynis - Security auditing and hardening tool, for UNIX-based systems.
SeKey - Use Touch ID / Secure Enclave for SSH Authentication.
SOPS - Editor of encrypted files that supports YAML, JSON, ENV, INI and BINARY formats and encrypts with AWS KMS, GCP KMS, Azure Key Vault and PGP.
ClusterFuzz - Scalable fuzzing infrastructure which finds security and stability issues in software.