AuthProxy
I've been working on AuthProxy, an open source embedded integration-platform-as-a-service. It has an embedded connector marketplace that lets you connect to 3rd party systems, then provides a proxy that handles the credentials automatically. Been working on it for a couple of years and in the last month or so have been trying it out to build an MCP gateway for some internal tooling. https://github.com/rmorlok/authproxy