Delta Chat vs SimpleX Chat

Delta Chat is a free, open-source instant messaging app for mobile and desktop, with support for self-hosting. It runs on Android, iOS, Linux, macOS and Windows, and supports multiple profiles and devices. Messages travel through secure, interoperable chatmail relays and are end-to-end encrypted by default, including attachments and their metadata. Delta Chat uses a subset of OpenPGP with Secure-Join and Autocrypt. Servers can still see sender and receiver addresses and message size; other message, contact and group metadata is encrypted. Chats can include interactive web apps for gaming and collaboration. Android and iOS audio and video calls use peer-to-peer WebRTC, but a March 2026 post said the feature was still behind a debug setting. A classic email address can act as a relay only if used exclusively by chatmail clients, and classic email providers generally do not support push notifications. The FAQ says there are no immediate plans for a web client. The project links to a forum for support and feedback.

SimpleX Chat is a messaging application for the SimpleX platform, with apps for Android, iOS, Linux, macOS, and Windows. It supports encrypted text with Markdown and editing, media and file sharing, decentralized groups, voice messages, disappearing messages, and audio and video calls. The network does not assign profile identifiers such as phone numbers or usernames. Messages and metadata use end-to-end encryption with continuous post-quantum key exchange. Four servers participate in each chat so relay servers cannot see which IP addresses communicate. Profiles, contacts, and messages remain in a portable encrypted database on user devices; relay servers hold encrypted messages only until delivery. Users may operate their own servers and still reach people using preconfigured servers. Developers can build bots and integrations using protocol SDKs; the TypeScript SDK connects to the Chat CLI over a WebSocket API. A phone or tablet can link to the desktop app only when both devices share a local network. Disappearing messages and recipient-side deletion are not guaranteed when a recipient device is offline or modified. The free plan costs nothing.