Force IIS to redirect requests to URLs with, or without, a trailing slash to enforce consistent URL structure, can be good for SEO.
Remove Trailing Slash
To always remove an ending slash from the URL, add the following to web.config’s <rules> section:
<system.webServer>
<rewrite>
<rules>
<rule name="Remove trailing slash" stopProcessing="true">
<match url="(.*)/$" />
<conditions>
<add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
<add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
</conditions>
<action type="Redirect" redirectType="Permanent" url="{R:1}" />
</rule>
</rules>
</rewrite>
</system.webServer>
For SEO purposes, this type of redirect should be Permanent (301).
Enforce Trailing Slash
To always add a slash to end of a URL if it doesn’t already end with one, add the following to web.config’s <rules> section:
<system.webServer>
<rewrite>
<rules>
<rule name="Add trailing slash" stopProcessing="true">
<match url="(.*[^/])$" />
<conditions>
<add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
<add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
</conditions>
<action type="Redirect" redirectType="Permanent" url="{R:1}/" />
</rule>
</rules>
</rewrite>
</system.webServer>
For SEO purposes, this type of redirect should be Permanent (301).