Delta Chat vs Olvid

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.

Olvid is an instant messaging app for text messages and attachments, available on Android, iOS, Linux, macOS, web, and Windows. Olvid says it does not require identifying details such as a phone number, email, name, address, or birth date. It also says messages and metadata are end-to-end encrypted, so it cannot know who is communicating with whom. Each message and file uses a single-use ephemeral key, intended to protect message history if a key is compromised. The app supports synchronization across devices without a master device. Secure audio and video calls are end-to-end encrypted; video calls support up to two contacts, while group audio calls have no participant limit. Receiving calls is free, and initiating them is free during a one-month trial that ends without billing or automatic subscription. The free plan includes unlimited messages and attachments, group discussions, ephemeral messages, multiple profiles, and inbound calls. Business costs €990 a year; Enterprise costs €990.50 a year.