imo vs SimpleX Chat

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.

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.