Tools

Browser Extension
This plugin adds alliance data to the Screeps website using either Tampermonkey or Greasemonkey.
Steam Client Extension
This plugin adds alliance data to the Screeps Steam Client by using the game console to inject the code into the client.
Public Segments
The in game user "LeagueOfAutomatedNations" has a copy of several API end points in public segments. See the API page for a list.