Size Up! by Sons of Selvedge

Unlike generic size charts, Size Up! uses an AI agent that knows your body and your wardrobe. Paste any product link and get a size rec based on garments you already own and love — not guesswork. Built for shoppers of smaller, heritage brands (raw denim, Goodyear-welted boots) where fit varies wildly and sizing feels like a gamble. You can even ask the agent follow-up questions, like chatting with a knowledgeable fit specialist.