Underwear Expert is a subscription-based e-commerce company that specializes in men's underwear. Founded by Michael Kleinmann in 2011, it started as a blog offering style advice and has since evolved into a curated subscription service featuring over 50 brands. The company emphasizes high-quality, well-fitting underwear, catering primarily to gay men and the LGBTQ+ community.

The product range includes various styles such as briefs, boxer briefs, jockstraps, and thongs, all marketed with a bold and joyful approach. Underwear Expert also offers complementary products like grooming items, lubricants, dietary supplements, and adult toys, creating a comprehensive lifestyle brand. The company is known for its rigorous quality vetting process and uses proprietary technology to provide personalized underwear selections based on customers' preferences.

Under the leadership of Kleinmann, who has extensive experience in the underwear industry, Underwear Expert has influenced market trends by encouraging brands to expand their size ranges and styles. The company focuses on inclusivity and aims to provide a curated shopping experience for men who appreciate both functionality and fashion in their underwear choices.