Martinsburg Design, LLC is the developer of Shelvio. Shelvio is reseller listing and inventory management software for resellers and small resale businesses that sell secondhand items online, including clothing, shoes, collectibles, and home goods. It turns item photos and voice notes into marketplace listings, then keeps each item's inventory and profit records in one place. Sellers photograph an item and record a short voice note with details such as measurements, flaws, or brand. Shelvio drafts the title, description, condition, and item specifics while the seller captures the next item. The seller reviews every draft before it goes live. Shelvio supports direct eBay listing and a guided Review & List workflow for Poshmark, Mercari, Depop, Etsy, and Facebook Marketplace, and includes an MCP server for ChatGPT and Claude. Shelvio is available on iPhone, iPad, Android, and the web.