Kate Maloney turned a business started on a lark into one of the world's largest online retailers.

In 2001, Matthew Maloney, Kate Maloney's brother, had developed Static Advantage, a search-engine optimization technology. As a test site, he started Matthew's Robes, a Web site that sold monks' robes.

Matthew Maloney brought in Kate Maloney, a recent BYU business school graduate, to run the site while he tested his "real" product.

But Kate Maloney realized the business could tap into a huge online market for costumes. A name change, a massive expansion of products and a few years later, Lindon-based Costume Craze is dominant in its field.

But in those same years, the online costume business has become highly competitive. To stay ahead of the pack, Costume Craze is continually updating its product mix — up to 1,000 new products are introduced each year — and its business practices.

The company still uses Static Advantage and has a proprietary technology that uses complex algorithms to determine what products, and how many of them, it should order.

Costume Craze also operates a network of related Web sites to optimize search-engine hits, and sells on eBay and Amazon.com. The company manufactures its own exclusive costume lines and made-to-order mascots, and unlike many competitors sells accessories like makeup, shoes and jewelry.

Also unlike many competitors, Costume Craze ships worldwide and is planning country-specific Web sites to take advantage of local cultures' costuming occasions.