{{Header}}
{{Title|title=
Delta Chat
}}
{{#seo:
|description=Delta Chat in {{project_name_short}}.
|image=DeltaChat_Logo_Small.png
}}
{{chat_mininav}}
[[File:DeltaChat_Logo_Small.png|thumb]]
{{intro|
Delta Chat in {{project_name_short}}.
}}
== Overview ==

[https://delta.chat/en/ Delta Chat] is a wrapper around email and GPG that provides chat client functionality. The client is Freedom Software, licensed under the GNU GPLv3 license.<ref>Client license: https://github.com/deltachat/deltachat-desktop/blob/main/LICENSE</ref> Supported features include text and voice messages, image and file sharing, direct messaging, and group chats.

Delta Chat uses the same protocols traditionally used by email for client-to-server communication. As such, theoretically any email service can be used as a Delta Chat server, even if it was not intended for this purpose. However, to facilitate anonymous use and easier onboarding, Delta Chat provides a server implementation known as [https://github.com/chatmail/relay chatmail], which configures traditional open-source email server software for use as a Delta Chat server. The server is open-source, licensed under the MIT license.<ref>Server license: https://github.com/chatmail/relay/blob/main/LICENSE</ref>

One notable Delta Chat feature is the ability to send packaged web applications as messages. These applications are shared as [https://webxdc.org/docs/ WebXDC packages], and allow the chat experience to be extended in arbitrary ways with limited network access. The privacy impact of WebXDC applications has not yet been investigated.

Advantages of Delta Chat:

* End-to-end encryption is mandatory and pervasive for sent messages when using chatmail servers.<ref>It is possible to receive and read unencrypted messages, which may be sent to a Delta Chat user via a traditional email client. However, chatmail servers will refuse to allow unencrypted messages to be sent as per the [https://github.com/chatmail/relay/blob/main/README.md chatmail README].</ref> Encryption may not be mandatory when using traditional email servers.
* Users are heavily encouraged (though not required) to use QR codes or invite links for establishing connections, which acts as an out-of-band key sharing mechanism to prevent MITM attacks.
* Chats where all users have E2EE keys properly shared will display a green checkmark badge. Rooms without this badge contain at least one user whose keys have not been verified out-of-band.
* Users unable to verify out-of-band can fall back to "trust on first use" key sharing by simply sharing an invite link in an unverified chat. This will cause the chat connection to be marked as verified.
* Messages are encrypted with GPG, providing decent security, though not as robust as double-ratchet encryption.
* It is very easy to create anonymous user accounts - Delta Chat will allow you to create an account on the default server (nine.testrun.org) by providing only a username. A randomly generated email address will be provided for newly created accounts. Other chatmail servers exist and can be used similarly.

Known disadvantages include:

* Quantum-resistant encryption is not yet available.
* Group chats feature no moderation safeguards - any user can kick any other user from a shared room or delete anyone else's messages. This makes Delta Chat unsafe for communities where untrusted users may be present in a room.
* Releases on Github are [https://github.com/deltachat/deltachat-desktop/issues/1504 not yet signed].
* No support for voice or video calls.
* Accounts are server-local and thus vulnerable to loss if a server goes down.

{{mbox
| image   = [[File:Ambox_warning_pn.svg.png|40px]]
| text    =

Delta Chat intentionally does not provide a way to import secret keys from an external device. It is therefore not easy to use Delta Chat in live mode without creating an account in persistent mode first, unless you are willing to lose all encryption keys on every reboot. Logging into a chatmail account without secret keys has not yet been tested.
}}

== Installation ==

Delta Chat's desktop client can be installed via the official Flatpak package. Ensure that the Flatpak package manager is installed and the Flathub repository is enabled:

{{Flatpak Install|package=
chat.delta.desktop
}}

You may have to log out and log back in before Delta Chat appears in the application menu.

Other ways to install and run Delta (AppImage, deb package) and current installation guides can be found on [https://delta.chat/en/download Delta Chat's download page]. Note that non-Flatpak packages do NOT automatically update when updating other packages on the system.

== Tips ==
=== Using non-default servers ===

By default, Delta Chat will use nine.testrun.org for new accounts. This is convenient, but users may prefer to use a different server to avoid the pitfalls of centralization and prevent overloading a single server.

The Delta Chat website provides [https://delta.chat/en/chatmail a list of alternate public chatmail servers] that can be used. To create an account using one of them:

'''1.''' Click on the link to the service to view the service's website.

'''2.''' Right-click on the account creation QR code on the service's website. This code will usually, though not always, have a Delta Chat logo in the middle of it.

'''3.''' Click "Copy Link".

'''4.''' On the Delta Chat account creation wizard's first screen, click "Create New Profile".

'''5.''' Click "Use Other Server".

'''6.'''' Click "Scan Invitation Code".

'''7.''' Click "Paste".

'''8.''' Click the "About profiles on example.com" link in the wizard to view the server's terms of service. (example.com will be replaced with the web address of the chosen chatmail service.)

'''9.''' Enter your desired username, and click "Agree & Create Profile".

'''10.''' Done.

The process of creating a Delta Chat account on a non-default server is now complete.

= Footnotes =
{{reflist|close=1}}
{{Footer}}
[[Category:Documentation]]