Delta Chat vs Threema
Delta Chat
delta.chat
Threema
threema.comSide by side
| Figure | Delta Chat | Threema |
|---|---|---|
| Price from | Free | $3/mo |
| Free plan | Yes | — |
| Free trial | — | Yes |
| Open source | — | — |
| Web | — | Yes |
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| iOS | Yes | Yes |
| Android | Yes | Yes |
| API | — | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 1 | 4 |
| Spec score · Encrypted Messaging Apps | 8.3 (#4) | 7.9 (#18) |
| Spec score · Secure Messaging Apps | 8.2 (#11) | 8.0 (#17) |
| Encryption | All messages are end-to-end encrypted by default, and attachments and their metadata are included in the encryption. | Threema provides end-to-end encryption for messages, media, calls, profile pictures, group names and group-member lists. |
| Headquarters | Freiburg, Germany | Pfäffikon SZ, Switzerland |
| Integrations | Delta Chat supports chatmail relays and in-chat web apps, and can use a classic email address as a relay with limitations. | Threema Gateway lets companies integrate Threema into existing software to send, receive and process messages. |
| Messaging | The app supports multi-profile and multi-device use, and relays messages through secure, interoperable chatmail relays. | Threema supports text and voice messages, voice and video calls, group calls, media sharing, file transfers and desktop use. |
| Security audits | The project says its encryption and network components have undergone multiple independent security audits, including audits in 2024. | Threema says its apps undergo regular audits by recognized security experts, including Cure53 audits in 2020 and 2024. |
| Support | The site links to a Delta Chat forum for support and feedback. | Threema provides support forms for the private app and management-cockpit support for Threema Work, plus dedicated Gateway and Broadcast support addresses. |
Plans
Threema
- Core$3 a month
- Professional$5 a month
- Private$6, paid once
- OnPremPriced on request
In their own words
Delta 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.
Threema
Threema is a paid messaging service for private and business communication, supporting text and voice messages, voice and video calls, group calls, media sharing and file transfers. It can be used without a phone number or email address, and contact synchronization is optional. End-to-end encryption covers messages, media, calls, profile pictures, group names and group-member lists. The apps are open source, with repositories for Android, iOS, macOS, Windows, Linux and Threema Web. The regular desktop app and web client require a mobile device with Threema installed and activated. Threema operates its own servers in Zurich data centers of an ISO 27001-certified colocation partner. It says its apps receive regular audits by recognized security experts, including Cure53 audits in 2020 and 2024. Business tools include Gateway integrations, Work APIs and Broadcast features such as feeds, distribution lists, bots and managed group chats. Private use costs $6, paid once, with price varying by app store and country; Core starts at $3 a month billed annually. A 30-day trial is listed.