Delta Chat vs imo
Delta Chat
delta.chatimo
imo.imSide by side
| Figure | Delta Chat | imo |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | — | Yes |
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | Yes | — |
| iOS | Yes | Yes |
| Android | Yes | Yes |
| Self-hosted | Yes | — |
| Plans published | 1 | 1 |
| Spec score · Encrypted Messaging Apps | 8.3 (#4) | 8.2 (#10) |
| 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. | imo offers free HD audio and video calls over the internet, including international calls. |
| Headquarters | Freiburg, Germany | Palo Alto, California, United States |
| Integrations | Delta Chat supports chatmail relays and in-chat web apps, and can use a classic email address as a relay with limitations. | The privacy policy describes iOS integration with Siri and access to iCloud Drive for sharing files. |
| Messaging | The app supports multi-profile and multi-device use, and relays messages through secure, interoperable chatmail relays. | Chats support real-time messages, photo, video and voice-recording sharing, and group chat. |
| Platforms | The download page lists Android, iPhone/iPad, macOS, Windows, GNU/Linux, and a community-driven Ubuntu Touch effort. | imo lists Android, iOS, Windows and Mac downloads, and its FAQ also describes using imo Web in a browser. |
| Product | Delta Chat is a reliable, decentralized and secure instant messaging app for mobile and desktop. | imo is an instant communication app for calls and messages. |
| Support | The site links to a Delta Chat forum for support and feedback. | The download FAQ directs users who need help to [email protected]. |
Plans
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.
imo
imo is a communication app for internet calls and messaging, available on Android, iOS, macOS, web, and Windows. It offers HD audio and video calls, including international calls, and group video calls for up to 20 participants with no fixed time limit. Chats support real-time messages, photos, videos, voice recordings, and group conversations; its Big Group feature supports up to 5,000 members. Stories hold photos, videos, and text updates for 24 hours. Listed privacy features include end-to-end encryption, Time Machine, and disappearing messages, while account controls include two-step verification and spam blocking. Encryption coverage is mixed. Instant message translation is available, and the privacy policy says Google Translate may provide it. That policy also says imo collects usage data, including communication partners, times, and message content. On iOS, imo integrates with Siri and can access iCloud Drive for file sharing. The app is free, though mobile carrier data charges may apply to internet calls.