How to redirect a international domain to a subfolder on the English site without hurting Google rankings?

Question

I have two sites:

• www.example.de
• www.main.com

www.main.com is English version of www.example.de which is in German. I want to keep only www.main.com. For the English version I will keep www.main.com, but for German I want to move it to www.main.com/de.

I am wondering what would be best solution for old www.example.de:

1. Redirect everything from www.example.de to www.main.com/de using 301 redirect?
2. Redirect everything from www.example.de towww.main.com/de/page-url-of-old-size.html? So each link actually get own address. Is that necessary or will Google realize where the page belongs on new site even if I redirect everything to home page?
3. Any other solution, maybe just set in Google webmaster tools the new domain or anything like that?

Answer 1

You must implement 301 redirect sending every url to its matching new url, by every means do not send everything to the homepage of your new german site, that's not user friendly and googlebot will be disappointed.

To accomplish this it will be good idea to keep exact url matching, adding your old urls into your new website:

www.example.de/page-url => www.main.com/de/page-url

If you keep your old urls, it will make your life easier because you just need to take your path, and then add your new host and folder.

In Google Webmaster Tools you can tell Googlebot your site has been moved. Look over here and here.