Some Piwik users automatically provide their CMS customers with Piwik statistics. If you want to provide a one-click automatic login to Piwik for your users, you can use the ‘logme’ mechanism, and pass their login & the md5 string of their password in the URL parameters:

/pathpiwik/index.php?module=Login&action=logme&login=your_login&password=your_MD5_password

This will log the user (create a cookie in their browser) and redirect to the index.php on succesful login. We advise to do this authentication over HTTPS. Note that this authentication method doesn’t work for a user with Super User access.
You can also specify the URL to redirect after a successful login, if different from the default Piwik dashboard page:

/pathpiwik/index.php?module=Login&action=logme&login=your_login&password=your_MD5_pwd&url=http://piwik.mycompany.com/subpath/

You can also specify an idSite (website ID) to load by default after the redirect:

/pathpiwik/index.php?module=Login&action=logme&login=your_login&password=your_MD5_pwd&idSite=145