Delta Chat
Delta Chat is a free, open-source instant messaging app for mobile and desktop, available on Android, iOS, Linux, macOS, and Windows, with self-hosting also …
What Delta Chat is
Delta Chat is a free, open-source instant messaging app for mobile and desktop, available on Android, iOS, Linux, macOS, and Windows, with self-hosting also listed. It supports multiple profiles and devices and relays messages through secure, interoperable chatmail relays. Messages are end-to-end encrypted by default, including attachments and their metadata, using a secure 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. Audio and video calls on Android and iOS use peer-to-peer WebRTC, but the feature was still behind a debug setting in a March 2026 post. A classic email address can be used as a relay only when 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.
Good
- Free and open-source software.
- Messages and attachments are encrypted by default.
- Supports multiple profiles and devices.
- Available on Android, iOS, Linux, macOS, and Windows.
Watch out
- There are no immediate plans for a web client.
- Calls were still behind a debug setting in March 2026.
- Classic email relays generally lack push notifications.
Who it suits
Delta Chat suits people seeking a free messaging app across mobile and desktop platforms, including those who want end-to-end encryption by default. It may not suit people who need a web client or dependable push notifications through a classic email provider.
Verdict
Delta Chat offers encrypted messaging across several mobile and desktop platforms, with chatmail relays and in-chat web apps. Note the stated limits around classic email relays, calls, and web access.
Plans and prices
From Delta Chat's own pricing page, checked 1 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Delta Chat | Free | Free and Open Source software |
The facts
Each one read from Delta Chat's own pages, with the date it was checked.
What it does
- 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.checked 1 Oct 2026
- 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.checked 1 Oct 2026
- Encryption
- All messages are end-to-end encrypted by default, and attachments and their metadata are included in the encryption.checked 1 Oct 2026
- Encryption standards
- Delta Chat uses a secure subset of OpenPGP with Secure-Join and Autocrypt to establish end-to-end encryption.checked 1 Oct 2026
- Integrations
- Delta Chat supports chatmail relays and in-chat web apps, and can use a classic email address as a relay with limitations.checked 1 Oct 2026
- Maintainer
- The imprint identifies Delta Chat as an open source community project and lists merlinux GmbH in Freiburg, Germany as responsible for website content.checked 1 Oct 2026
- Messaging
- The app supports multi-profile and multi-device use, and relays messages through secure, interoperable chatmail relays.checked 1 Oct 2026
- 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.checked 1 Oct 2026
- Product
- Delta Chat is a reliable, decentralized and secure instant messaging app for mobile and desktop.checked 1 Oct 2026
- Security audits
- The project says its encryption and network components have undergone multiple independent security audits, including audits in 2024.checked 1 Oct 2026
- Support
- The site links to a Delta Chat forum for support and feedback.checked 1 Oct 2026
- 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.checked 1 Oct 2026
The company
- Headquarters
- Freiburg, Germanychecked 28 Sep 2026
Where it runs
- In-chat apps
- Delta Chat supports interactive web apps in chats for gaming and collaboration.checked 1 Oct 2026
- Platforms
- The download page lists Android, iPhone/iPad, macOS, Windows, GNU/Linux, and a community-driven Ubuntu Touch effort.checked 1 Oct 2026
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