BlackBox is described as 'Safely store secrets in a VCS repo (i.e. Git, Mercurial, Subversion or Perforce). These commands make it easy for you to Gnu Privacy Guard (GPG) encrypt specific files in a repo so they are "encrypted at rest" in your repository' and is an app. There are nine alternatives to BlackBox for a variety of platforms, including Mac, Linux, Windows, Self-Hosted and SaaS apps. The best BlackBox alternative is Vault by HashiCorp. It's not free, so if you're looking for a free alternative, you could try Vault by HashiCorp or Bitwarden Secrets Manager. Other great apps like BlackBox are Rot, AWS Secrets Manager, elasticdog/transcrypt and gcrypt.