Web.Config for running Wordpress as a subdirectory on IIS. Additionally, created support for accessing the REST API, which changes routes to match the Site URL.

gistfile1.txt

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <rewrite>
      <rules>
        <rule name="static" patternSyntax="Wildcard">
          <match url="*"/>
          <conditions>
	    <add input="{REQUEST_URI}" matchType="Pattern" pattern="/wordpress/*" negate="true" />	
 	    <add input="{REQUEST_URI}" matchType="Pattern" pattern="/wp-json/*" negate="true" />
            <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true"/>
            <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true"/>
          </conditions>
          <action type="Rewrite" url="index.html" redirectType="Found"/>
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
  <location path="wordpress">
    <system.webServer>
      <rewrite>
        <rules>
          <remove name="wordpress" />
          <rule name="wordpress" patternSyntax="Wildcard">
            <match url="*"/>
            <conditions>
              <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true"/>
              <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true"/>
            </conditions>
            <action type="Rewrite" url="wordpress/index.php" redirectType="Found"/>
          </rule>
        </rules>
      </rewrite>
    </system.webServer>
  </location>
  <location path="wp-json">
    <system.webServer>
      <rewrite>
        <rules>
          <remove name="api" />
          <rule name="api" patternSyntax="Wildcard">
            <match url="*"/>
            <conditions>
              <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true"/>
              <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true"/>
            </conditions>
            <action type="Rewrite" url="wordpress/index.php" redirectType="Found"/>
          </rule>
        </rules>
      </rewrite>
    </system.webServer>
  </location>
</configuration>