A small sample of the options available for selling/buying second-hand:

Online:

• LabelCrush (Belgium): online platform reselling designer clothes
• Vaniitas (Belgium): online platform reselling designer clothes
• Labels Inc (Belgium): online platform (and offline retail outlet) reselling designer clothing
• My Kids Factory (Belgium): online platform reselling designer kids clothes
• The Next Closet (the Netherlands): online platform reselling designer clothes
• United Wardrobe (the Netherlands): online platform reselling vintage clothes
• Vestiare Collective (France): online platform reselling luxurious clothes
• Asos Marketplace (UK): online platform reselling clothes
• Closet49 (Kenya): online platfrom reselling clothing
• Otters en Flamingo's (Belgium): online platform reselling children and baby clothes 
• Cazou (the Netherlands): online platform reselling clothing for young parents 
• Traditional second-hand sites with separate sections for clothing, such as eBay and 2dehands.be

Offline:

• Think Twice has more than 10 second-hand stores all over Belgium
• De Kringwinkel
• Several local initiatives reselling designer clothing, such as Rosier41 in Antwerp, to name just one example.
• ‘Netwerk Bewust Verbruiken’ (conscious consumer network) offers a list with extra inspiration on where to buy and sell second-hand items.
• Closet Sale @ Kerk Gent is an event every two months, where you can buy and resell clothing in a cosy setting.