“We wanted users to be able to collaborate with their insurance companies, their estate planners or an auction house if they’re trying to sell the work,” he said. “We wanted the barrier to entry to be low; a lot of the people we were working with were less tech savvy.”

(The service charges a monthly fee based on the size, not the value, of the collection. It goes up to $19 a month for individuals and $96 a month for institutional collectors.)

Geoffrey Koslov, a collector and co-owner of a Houston photography gallery, Foto Relevance, uses the Artwork Archive system for the works of artists he represents. He did it to manage his business as well as for insurance coverage.

But like many collectors, his personal collection is still listed in “binders and folders and a manual spreadsheet” — all things that could be destroyed in a flood, as was his own home in 2001 when a tropical storm flooded Houston. (He rebuilt his home higher, he said, and has weathered subsequent floods.)

There are many services that help owners and artists catalog their works , like Art Galleria, Artlogic and Veevart. Art advisers like the Winston Art Group, among the largest independent art appraisers in the United States, also have their own proprietary systems.

Most important to collectors, though, is keeping what they own confidential.

“If you’re going to have a location, a picture a description and a value of a piece of art, the most important part is confidentiality,” said Shanna Hennig, director of the Southwest region for Winston Art Group. Otherwise, the online system risks being a guidebook for art thieves.

Her group will catalog a collection while appraising it and consulting on buying and selling pieces. Ms. Hennig said that work revealed how lax some private collectors can be and the risk that poses.