Delta Chat

Name: Delta Chat
Brand: Delta Chat

An encrypted messenger that runs over standard email servers instead of a proprietary network.

softwareMessaging Apps open-sourceencrypted-messagingemail-based

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Our Verdict

Best for

Privacy-first users who want encrypted messaging without new phone numbers or accounts, reusing email infrastructure.

Skip if

You need a messenger with a huge existing contact network or polished enterprise support.

What is Delta Chat?

Delta Chat is a free, open-source messaging app that delivers end-to-end encrypted chats over the existing email network instead of a proprietary server infrastructure. Any two Delta Chat users can message each other using just an email address, with the app handling the IMAP/SMTP plumbing invisibly in the background so it feels like a normal chat app. The project also runs dedicated "chatmail" relay servers for people who want an account without an existing email address, and supports multi-device sync, audited end-to-end encryption, and small in-chat web apps (webxdc) for games and simple tools. Because it rides on open Internet standards rather than a single company's servers, no account can be shut down by one vendor and the core client is developed in the open on GitHub.

SpecificationsAI-estimated

open source✅ Yes

api available❌ No

support optionsCommunity forum, GitHub issues

key integrationsIMAP/SMTP email servers, chatmail relay servers, webxdc mini-apps

Key Features of Delta Chat

Delivers fully end-to-end encrypted messaging using the Autocrypt/OpenPGP standard layered on top of ordinary email transport.

Lets any user sign up with an existing email address, so there is no separate account system to trust or lose access to.

Offers official chatmail relay servers for people who want a Delta Chat-only identity without a traditional inbox.

Syncs conversations, contacts, and read state across multiple devices tied to the same account.

Supports small interactive mini-apps called webxdc that run inside a chat for games, polls, and collaborative tools.

Provides group chats, voice messages, file transfer, and location sharing comparable to mainstream chat apps.

Publishes its core Rust library and clients as open source on GitHub for independent security review.

Runs natively on Android, iOS, Windows, macOS, and Linux without requiring a phone number to register.

Use Cases for Delta Chat

Privacy-focused personal messaging

Individuals who want encrypted chat without handing a phone number or metadata to a big tech company.

Communicating over an existing email account

Users who prefer to reuse an email address they already control instead of creating a new proprietary account.

Censorship-resistant communication

People in regions where mainstream messaging apps are blocked can often still reach email/chatmail infrastructure.

Lightweight collaborative mini-apps

Small teams using in-chat webxdc apps for simple polls, games, or shared tools without installing separate software.

Pros & Cons of Delta Chat

Pros

Completely free with no ads, subscriptions, or data monetization.
Works over infrastructure the user already controls (their own email/chatmail server), avoiding vendor lock-in.
Open-source codebase lets security researchers audit the encryption implementation.
No phone number required to create an account, unlike most mainstream messengers.

Cons

Network effect is small compared to WhatsApp, Telegram, or Signal, so contacts must also install it.
Email-based transport can feel slower or clunkier than purpose-built messaging protocols for some users.
Group and multimedia features are less polished than dedicated chat apps with larger engineering teams.

Frequently Asked Questions

Is Delta Chat really free?

Yes, the app itself is free and open source; you only pay for whatever email or chatmail hosting you choose to use.

Do I need an email account to use Delta Chat?

No, you can sign up through a Delta Chat chatmail relay server instead, or use an existing email address if you prefer.

Is Delta Chat as secure as Signal?

It uses audited end-to-end encryption, though its trust model differs since messages travel over email/chatmail infrastructure rather than a single proprietary network.

Can I message WhatsApp or Telegram users from Delta Chat?

No, Delta Chat only communicates with other Delta Chat users or compatible email-based clients, not with closed messaging networks.

Pricing Overview

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Free

Detailed plans are not listed. Visit the official website for pricing information.

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Top Alternatives & Similar Software

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SimpleX Chat

AI-suggested

SimpleX Chat is an open-source, end-to-end encrypted messenger built around a network design with no persistent user identifiers of any kind, not even random ones. Messages are relayed through servers that see only noise, so there is no phone number, username, or account ID for anyone, including SimpleX, to tie back to a person. The app supports one-to-one and group chats, audio and video calls, file transfer, and multiple chat profiles, and it can run on self-hosted servers for organizations that want full control over their infrastructure. Its protocol and clients are fully open source and have been independently security-audited by Trail of Bits.

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