Vault is a very popular, open source credential manager that supports tokens, passwords, certificates, API keys and others. Please consider integration with Royal TS.
More info: https://www.vaultproject.io/
"Vault secures, stores, and tightly controls access to tokens, passwords, certificates, API keys, and other secrets in modern computing. Vault handles leasing, key revocation, key rolling, and auditing. Through a unified API, users can access an encrypted Key/Value store and network encryption-as-a-service, or generate AWS IAM/STS credentials, SQL/NoSQL databases, X.509 certificates, SSH credentials, and more."