KeyNexus - KeyNexus is a cloud-based encryption-key storage and provisioning service purpose-built for developers of cloud-based applications.
EnvKey - Protect API keys and credentials. Keep configuration in sync everywhere.
Dogtag PKI - The Dogtag Certificate System is an enterprise-class open source Certificate Authority (CA).
KeePass - KeePass is an open source password manager. Passwords can be stored in highly-encrypted databases, which can be unlocked with one master password or key file.
Vault by HashiCorp - Tool for managing secrets
VAULT - A password manager for freelancers, developers, agencies, IT departments and teams. VAULT safely stores account information and makes it easy to share between co-workers, other team members and clients.