Elinor Mills/CNET

Making good on her promise, California Attorney General Kamala Harris has continued her crackdown on mobile-app developers and companies for not doing more to ensure users' privacy. She announced today that she'll be sending letters to 100 app developers and companies to formally notify them that they're violating California's privacy laws.

"Protecting the privacy of online consumers is a serious law enforcement matter," Harris said in a statement today. "We have worked hard to ensure that app developers are aware of their legal obligations to respect the privacy of Californians, but it is critical that we take all necessary steps to enforce California's privacy laws."

The California Online Privacy Protection Act dictates that all apps must post a privacy policy notice that lets users know what personal information is being collected and how that information is being used. It also requires that users be given the opportunity to read the privacy policy before downloading the app. The goal of this law, which is one of the strongest consumer privacy laws in the nation, is to safeguard users' private and personal information.

According to the Los Angeles Times, some of the popular app developers to receive the Harris' letter are United Airlines, Delta Airlines, and Open Table. Both United and Delta told the Times that they are actively working to make sure they are in compliance with California's law.

In February, Harris announced that Apple, Google, Microsoft, Amazon, Hewlett-Packard, and Research In Motion had agreed to improve mobile privacy protections, starting with requiring privacy policies in apps. Facebook joined the roster in June.

If the 100 companies on Harris' list don't post a privacy policy notice on their app within the next 30 days, they could face fines of up to $2,500 every time their app is downloaded.