BitChat Free plan 8.9 Visit 
Delta Chat
delta.chat
What it is
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.
Spec sheet
- Product
- Delta Chat is a reliable, decentralized and secure instant messaging app for mobile and desktop.Read 1 Oct 2026 · delta.chat
- Platforms
- The download page lists Android, iPhone/iPad, macOS, Windows, GNU/Linux, and a community-driven Ubuntu Touch effort.Read 1 Oct 2026 · delta.chat
- Integrations
- Delta Chat supports chatmail relays and in-chat web apps, and can use a classic email address as a relay with limitations.Read 1 Oct 2026 · delta.chat
- Support
- The site links to a Delta Chat forum for support and feedback.Read 1 Oct 2026 · delta.chat
- Headquarters
- Freiburg, GermanyRead 28 Sep 2026 · delta.chat
- Calls
- Audio and video calls on Android and iOS use peer-to-peer WebRTC with signaling through Delta Chat messages; the March 2026 post says the feature was still behind a debug setting.Read 1 Oct 2026 · delta.chat
- Classic email limitation
- The FAQ says a classic email address is supported only when used exclusively by chatmail clients, and classic email providers generally do not support push notifications.Read 1 Oct 2026 · delta.chat
- Encryption
- All messages are end-to-end encrypted by default, and attachments and their metadata are included in the encryption.Read 1 Oct 2026 · delta.chat
- Encryption standards
- Delta Chat uses a secure subset of OpenPGP with Secure-Join and Autocrypt to establish end-to-end encryption.Read 1 Oct 2026 · delta.chat
- In-chat apps
- Delta Chat supports interactive web apps in chats for gaming and collaboration.Read 1 Oct 2026 · delta.chat
- Maintainer
- The imprint identifies Delta Chat as an open source community project and lists merlinux GmbH in Freiburg, Germany as responsible for website content.Read 1 Oct 2026 · delta.chat
- Messaging
- The app supports multi-profile and multi-device use, and relays messages through secure, interoperable chatmail relays.Read 1 Oct 2026 · delta.chat
- Metadata
- The FAQ says servers can see sender and receiver addresses and message size, while other message, contact and group metadata is end-to-end encrypted.Read 1 Oct 2026 · delta.chat
- Security audits
- The project says its encryption and network components have undergone multiple independent security audits, including audits in 2024.Read 1 Oct 2026 · delta.chat
- Web client
- The FAQ says there are no immediate plans for a Delta Chat web client and points users to portable Windows or Linux AppImage clients when they cannot install software.Read 1 Oct 2026 · delta.chat
Plans and prices
Delta Chat Free Free and Open Source software Read 1 Oct 2026 · delta.chat
Strong points and limits
Strong points
- End-to-end encryption is enabled by default
- Attachments and their metadata are encrypted
- Supports mobile, desktop and self-hosted platforms
- Supports multiple profiles and devices
- Chats can include interactive web apps
Limits
- No immediate plans for a web client
- Calls were still behind a debug setting
- Classic email relays have limited support and push notifications
Who it suits
Delta Chat suits people who want encrypted messaging across mobile and desktop, including those who need multiple profiles or devices. It may also suit users interested in self-hosting or interactive apps within chats.
Verdict
Delta Chat offers default message encryption across a wide range of listed platforms, with chatmail relays and in-chat web apps. Call availability and classic email relay support have stated limitations.
Where Specifiction places it
- Encrypted Messaging Apps#4 of 438.3
- Secure Messaging Apps#11 of 368.2
