Bel-first contains information on 1,2 million companies in Belgium and 25,000 in Luxembourg. You can search on company name or industry and narrow your search on company size, geographic location,... It allows you to evaluate companies in detail, including peer group comparisons and get an insight into a specific sector.
NACE-Bel codes are used to identity the different industries. To get a quick overview of these codes, take a look at the Statistics Belgium website (in Dutch).