Messenger Comparison Table
This is not intended to be an extremely comprehensive list, but enough to get a grasp on the situation.
DivestOS includes Silence, a SMS only fork of Signal, it allows sending encrypted SMS messages to other users of Silence. It is not however recommended for use as your primary messaging client, and is there more as a fallback. The only client for now that we recommend is Conversations, a top notch XMPP client, fully supports the OMEMO XEP, is easy on the battery, and doesn't force you into a walled garden. It is not the easiest thing getting your friends and family to switch apps, so at the very least any apps with end-to-end encryption support should always be preferred over apps without.
As noted below the Signal protocol (double ratchet) is the current gold standard for end-to-end asynchronous messaging encryption.
| Name | FOSS Client | Non-Free Dependencies | FOSS Server | Protocol | Federated | Decentralized | Encryption | Encrypted by Default | Battery Drain | Data Usage | Desktop Client | File Sharing | Voice Calling | Video Calling |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Conversations | GPLv3 | No | Yes | XMPP | Yes | No | TLS + OMEMO (Double Ratchet) E2E | To contacts with OMEMO | Minimal | Minimal | Yes | Yes | Yes | Yes |
| Element/Riot | Apache | No | Yes | Matrix | Yes | No | TLS + Olm (Double Ratchet) E2E | Not yet | ? | ? | Yes | Yes | Yes | Yes |
| Signal | GPLv3 | Yes, GMS | Yes | Custom | No | No | TLS + Signal E2E | To contacts with Signal | ? | ? | Yes | Yes | Yes | Yes |
| Jami/Ring | GPLv3 | No | Yes | Custom | Yes | Yes | TLS + SRTP + Custom E2E | Yes | High | ? | Yes | Yes | Yes | Yes |
| Briar | GPLv3 | No | N/A | Custom | No | Yes | Custom E2E | Yes | High | ? | No | No | No | No |
| Silence | GPLv3 | No | N/A | SMS | Yes | Yes | Signal E2E | To contacts with Silence | Minimal | Minimal | No | Basic | No | No |
| Xabber | GPLv3 | No | Yes | XMPP | Yes | No | TLS + OTR E2E | No | Low | Low | Yes | Yes | No | No |
| Telegram | GPLv2 | Yes | No | Custom | No | No | Custom E2E | No | ? | ? | Yes | Yes | No | No |
| Kontalk | GPLv3 | No | Yes | XMPP | Yes | No | TLS + OpenPGP E2E | Yes | ? | ? | Yes | Yes | No | No |
| Delta Chat | GPLv3 | No | Yes | Yes | ? | TLS + OpenPGP E2E | To contacts with AutoCrypt | Low | Minimal | Yes | Yes | No | No | |
| Wire | GPLv3 | Yes | Yes | Custom | No | No | Custom E2E | Yes | ? | ? | Yes | Yes | Yes | Yes |
| Threema | AGPLv3 | Yes | No | Custom | No | No | Custom E2E | Yes | ? | ? | Web | Yes | Yes | No |
| No | Yes | No | Custom | No | No | TLS + Signal E2E | Yes | ? | ? | Web | Yes | Yes | No | |
| Google Allo | No | Yes | No | Custom | No | No | TLS + Signal E2E | No | ? | ? | No | Yes | No | No |
| Facebook Messenger | No | Yes | No | Custom | No | No | TLS + Signal E2E | No | ? | ? | Web | Yes | Yes | Yes |
| Google Hangouts | No | Yes | No | Custom | No | No | TLS | No | ? | ? | Web | Yes | Yes | Yes |
| Skype | No | Yes | No | Custom | No | No | TLS | No | ? | ? | Yes | Yes | Yes | Yes |