Here’s a (recently updated) incomplete list of commercial / companies registers in the EU and Switzerland from my bookmarks. Originally, I planned to include only “official” registers, but I’ve included other sites providing access to the registers’ data (and often further data), too.
You should be able to obtain information on certain types of companies on-line by visiting these sites (for more details, see directive 2003/58/EC). Searching is mostly free, but fees apply in many cases for viewing / downloading documents. Not all registers are equally comprehensive (yet?).
Austria: Firmenbuch (German only)
Belgium: Banque-Carrefour des Entreprises (in French and Dutch, free of charge). See also Coface Services Belgium.
France: The “Registre National du Commerce et des Sociétés (RNCS)” is mantained by the Institut National de la Propriété Industrielle (INPI). Official site: www.euridile.com (in French). See also Infogreffe (in French and English, fees apply), ORT (in French and English and Societe.com (free of charge).
Germany: The brand new Unternehmensregister is currently down now working again (in German), but you can also try the Handelsregister (in German, too, does not include the annual accounts).
Luxembourg: Registre de Commerce et des Sociétés (in French, free of charge).
Switzerland: Central Business Names Index – Zefix (in German, French, Italian, English)
United Kingdom: Companies House (in English)#
Other countries: Have a look at the following lists / websites: