Messaging apps Telegram and Signal saw a surge in the number of app downloads and active users amid a backlash over competitor WhatsApp’s new privacy policy.

Telegram added 25 million new users in the last 72 hours to reach the 500 million active users milestone, according to the messaging app’s official Twitter account on Wednesday.

Signal collected 7.5 million downloads from Apple’s App Store and Google Play period from Wednesday through Sunday, an equivalent to a 4,200 percent increase in the number of users, according to data analytics company Sensor Tower.

This came after WhatsApp presented new terms of service last week, asking users to agree to let parent company Facebook and its subsidiaries collect their data including phone numbers and locations before Feb. 8 to maintain access to the app.

WhatsApp’s new terms touched off a wave of criticism as some privacy activists took questioned the intention of collecting data and began switching to rival apps such as Telegram and Signal.

Since the backlash, WhatsApp has tried to clarify and reassure its users that the change does not affect the privacy of messages sent through the app.

“Our policy update describes business communication and adds transparency,” WhatsApp CEO Will Cathcart tweeted Tuesday. “It does not impact how people communicate privately with friends or family.”

“We want to address some rumors and be 100% clear we continue to protect your private messages with end-to-end encryption,” WhatsApp tweeted Tuesday.

But some still do not appear to buy the explanation from the messaging app company.

“Box #7 tends to cast doubt on the whole “we don’t store your data” sentiment,” Chris Vickery, Director of Cyber Risk Research at UpGuard, backfired on Twitter. “If WhatsApp doesn’t vacuum up user data and store it somewhere, then how can users then download their own data later on?”

Vickery’s referral to box number seven is the part in a FAQ on WhatsApp’s website where it says users can download their data and see what information the messaging app has on their accounts.

Even with the growth of the rival social media platforms and concerns about its privacy terms update, however, WhatsApp remains the largest messaging app in the world with over 2 billion users.

By Kan Hyeong-woo (hwkan@heraldcorp.com)