I found out I needed to add this in app/code/core/Mage/Api/etc/config.xml

under “adminhtml”

 <routers>
 <api>
 <use>standard</use>
 <args>
 <module>Mage_Api</module>
 <frontName>api</frontName>
 </args>
 </api>
 </routers>

Also need to turn off Auto-redirect to Base Url in System > Web > Url Options.

After this you can change the Admin URL to absolutely anything and it’ll work correctly in Unicommerce 🙂