In a statement to TechCrunch on Thursday, an Apple spokesperson said that the company’s “App Store Review Guidelines require that apps request explicit user consent and provide a clear visual indication when recording, logging, or otherwise making a record of user activity.” After an earlier TechCrunch report surfaced, suggesting that some popular apps are recording user interaction with their programs, the Apple spokesperson added that the company has “notified the developers that are in violation of these strict privacy terms and guidelines, and will take immediate action if necessary.”

The issue centers on a third-party analytics tool called Glassbox that several popular apps, including Expedia and Hotels.com, among others, use in their software. According to the TechCrunch report, Glassbox is capable of recording every tap, swipe, and text input a person puts into an app and then sends that information back to developers. The tool is designed to improve the user experience, but according to the TechCrunch report, it could also expose some user data, including customer credit cards.

In response, a Glassbox spokesperson said that the TechCrunch investigation was “interesting, but also misleading.” The company is not “spying on consumers,” the spokesperson said. Instead, Glassbox is providing customers with “tools that record and analyze user activity on web sites and apps.” The company believes the data it collects “helps companies better understand how consumers are using their services.”

“We are strong supporters of user privacy and security,” the spokesperson said. “Glassbox provides its customers with the tools to mask every element of personal data.”

Glassbox has a small social media presence on Twitter. The company’s Twitter profile description sheds light on how its service works: “Imagine if your website or mobile app could see exactly what your customers do in real time, and why they did it? This is Glassbox.”

TechCrunch obtained one of the e-mails Apple apparently sent to an app developer that had been using Glassbox. The e-mail, which TechCrunch published, said that the app “uses analytics software to collect and send user or device data to a third party without the user’s consent.” The e-mail reminded the developer about Apple’s guidelines requiring them to tell users when recording. Apple said the developer would need to remove the feature within a day and resubmit the app for approval.

It’s unclear whether the affected apps, which include some of the more popular retail and travel brands in the App Store, have complied with Apple’s request.

“”The protection of customer data and privacy is of the utmost priority to us. We can confirm that Expedia Group brands are not actively using Glassbox services on any of our native applications for iOS or Android,” an Expedia Group spokesperson told Fortune in a statement, representing both Expedia and Hotels.com. “On select Expedia Group brands native applications for Android, Glassbox exists from a prior proof of concept in the codebase but it has been disabled for some time and has not been actively capturing information.”

Neither Apple nor Glassbox immediately responded to a Fortune request for comment.

Update at 12:26 p.m. ET to include Expedia Group’s statement.