Overview Global Stamp Catalogues
Global Stamp Catalogues (books)
Stanley Gibbons Global Stamp Catalogues
Michel Global Stamp Catalogues
Scott Global Stamp Catalogues
Global Stamp Auctions/Marketplaces
Catawiki
Ebay
Stampden Global Stamps
Global/Worldwide Online Stamp Catalogues
Michel (German/English) – Most complete online stamp catalogue with actual prices (subscription required)
Colnect (all language) – Colnect (premium) has auto-matching, best matches and an extensive free stamp catalogs
Freestampcatalogue (English/German/French/Spanish/Dutch) – All official stamps since 1920 (with reference to Michel/Scott/Stanley Gibbons/Yvert) and for many countries pre-1920 stamps.
Perf48 (English) – Worldwide stamp database. Membership to take a data-driven approach to stamp collecting and track your collection online (USD 2.48/month)
Stampdata (English) – Wiki based free catalogue; stamps of 988 countries and areas and over 660,000 stamps.
StampWorld (Various) – The Facebook of Stamp Collectors; over 750,000 stamps.
Stamps of the World – Wiki based free catalogue; almost 400,000 pages