Check the privacy policies of the messaging services here.
Signal is an app developed by the Signal Foundation and Signal Messenger LLC, a non-profit company. The Signal app is a messaging service that asserts its focus on the privacy of users.
Moxie Marlinspike, the American entrepreneur and cryptographer, created the messaging service. He currently serves as the CEO of Signal Messenger.
Brian Acton, who co-founded WhatsApp, created the Signal Foundation with Moxie Marlinspike in 2017. Acton had left WhatsApp in 2017 and invested $50 million for funding Signal.
Telegram is a messaging service that was developed by the Durov Software Industry. This German company was founded by Nikolai Durov and Pavel Durov. The company was founded in 2013 in Russia and then moved its operations to Berlin. Pavel Durov currently heads the company.
The company currently has a user base of 300 million active users around the world.
Data Collection on Signal:
Signal states that it solely collects a user’s contact information. According to the privacy nutrition label on Apple Store, Signal only requires the user’s contact info, which is the user’s phone number.
The profile name and picture on Signal is end-to-end encrypted along with all messages and calls on the app exchanged. The messaging service has stated that it cannot decrypt the content of the user’s messages or calls.
The messaging service can optionally discover which contacts in the user’s address book are using Signal.
Data Collection on Telegram:
Telegram requires the Contact Information of the user, which is the phone number of the user. The messaging service also requires access to the contacts of the user along with the User ID.
The messaging service requires users to create a profile name, profile picture, and information in the about section. However, the service doesn’t require the user’s gender, real name, or age for operating the account.
Telegram users can submit an email for password recovery optionally. If they forget their login details, the service can send a password recovery mail.