Signal

Signal's listing is short, and its first line is a claim about the organisation rather than about a feature: it is "a messaging app with privacy at its core". It is the only one of the four reviewed here that names its own encryption protocol in the store listing, and the only one that tells you who pays for it — a 501(c)(3) nonprofit funded by donations rather than by advertisers or investors. The technical specifics are given without hedging: end-to-end encryption by default, group calls of up to 50 people and group chats of up to 1,000.

You send texts, voice messages, photos, videos, GIFs and files, and the listing notes that everything runs over your data connection, which is how it avoids SMS and MMS fees. Voice and video calls are encrypted, group calls hold up to 50 people, and group chats hold up to 1,000 with admin permission settings that control who can post and manage members. Stories are the ephemeral layer: image, text and video Stories disappear after 24 hours, and privacy settings govern who could see each one.

The app is free, and this is the one listing of the four that explains its economics instead of only asserting a price: Signal describes itself as independent and not for profit, a 501(c)(3) supported by donations. It describes no subscription, no premium tier and no paid feature, and because it also names where the money comes from, its free claim is the most complete answer to the question that any of these four gives.

Signal's safety section is the shortest of the four and the strongest, because it makes claims that can be checked against a published protocol and a public repository. It says the open-source Signal Protocol means it cannot read your messages or listen to your calls, and adds "neither can anyone else", followed by the plainest version of the promise in this batch: no back doors, no data collection, no compromises. It also states that it knows nothing about you or who you are talking to, which is a claim about collecting as little as possible rather than about encryption, and is the harder of the two to keep. What the listing does not describe is any moderation or reporting process, which is consistent with a service whose selling point is that it cannot see what passes through it.

People who want the encryption to be the default rather than a mode, and who care that the organisation running it is a nonprofit with a published protocol. Anyone who wants very large public groups, or a cloud archive of everything they have ever sent, is looking at the wrong app — that is what the other three are for.

The cleanest privacy claim of the four reviewed here, and the shortest listing, which is not a coincidence: Signal names its protocol, its funding and its limits rather than describing capabilities at length. End-to-end encryption is the default rather than an option, the group sizes are given as concrete numbers, and the nonprofit structure answers the question of who is paying and why. The trade is capability: there is no cloud archive and no group anywhere near Telegram's size, and the listing describes no moderation process at all.