* RaaS: Offering resale-as-a-service for brands like Everlane and Madewell. They helps merchants monetize returns. As e-commerce grows, so will this channel.

In the US alone, the secondhand fashion market could grow 20% between 2020 and 2025 to reach $67 billion in size, according to estimates by Business of Fashion Insights.

Thanks to increased consumer consciousness around sustainability, the circular economy, and fair labor, resale has become fashion’s hottest sector—and brands want in. But scaling and making resale profitable isn’t easy, and with increasing competition in the space, it’s only going to get harder.