Dreamwidth API
From Dreamwidth Notes
XML-RPC API
This is the page for the DW API documentation. There's nothing here right now, but you can check out the old LJ API documentation for a starting point for the old XML-RPC API. See also Category:XML-RPC Protocol
OpenAPI
There is a new API being created - e.g. see Adding API Routes. The original code is at https://github.com/dreamwidth/dw-free/pull/2265.
To create an API key, go to manage account -> mobile -> advanced options.