We host it at a subdomain:
<rule name="Ignore REST API from Redirects" enabled="true" stopProcessing="true">
<match url="^api/v2/" />
<conditions logicalGrouping="MatchAll" trackAllCaptures="false" />
</rule>
<rule name="Ignore other asp.net requests" enabled="true" stopProcessing="true">
<match url="\.(asmx|axd|ashx)" />
<conditions logicalGrouping="MatchAll" trackAllCaptures="false" />
</rule>
<rule name="Add trailing slash to folders (.com/b -> .com/b/)" enabled="true">
<match url="^([^.?]+[^.?/])$" />
<conditions logicalGrouping="MatchAll" trackAllCaptures="false">
<add input="{HTTP_HOST}" pattern="(.*)" ignoreCase="false" />
</conditions>
<action type="Redirect" url="{R:1}/" redirectType="Permanent" />
</rule>
<rule name="Redirect ../default.aspx to ../" enabled="false">
<match url="^([a-zA-Z0-9\-\._:/]*?/)?default.aspx(\?.*)?$" />
<conditions logicalGrouping="MatchAll" trackAllCaptures="false" />
<action type="Redirect" url="{R:1}{R:2}" redirectType="Permanent" />
</rule>
<rule name="Take requests without an extension and rewrite to ../default.aspx" enabled="true" stopProcessing="true">
<match url="^((?:.*?/)*[^.\?]*)(\?.*)?$" />
<conditions logicalGrouping="MatchAll" trackAllCaptures="false" />
<action type="Redirect" url="{R:1}default.aspx{R:2}" />
</rule>