If Sam Spade or Mike Hammer were around today, they’d probably be plumbers, thanks to a boom in Internet snooping, which lets savvy computer users do their own detective work instead of hiring a gumshoe to do it for them.

Some private detectives — there are about 8,700 in California — say their business has been stunted by the ability of people to use the Internet to gather information they used to hire a private eye to collect.