Major online retailers like Walmart, Costco, Best Buy, and Nordstrom are legitimate, publicly traded, and safe for shopping. While they are trustworthy, your experience may vary based on whether you buy first-party products or from their third-party marketplaces, so it is always wise to check individual seller ratings and specific return terms. For the best experience, prefer retailers with physical locations for easier returns and be mindful of return windows and potential shipping fees before you purchase.