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).
Vault by HashiCorp - Tool for managing secrets
Authy - Best rated Two-Factor Authentication smartphone app for consumers, simplest 2fa Rest API for developers and a strong authentication platform for the enterprise.
Vault on AWS - Store archives in a vault. You can create and delete vaults, get vault metadata, download vault inventory, and configure vault notifications.