What it does
Delta Chat is a messaging app that looks and behaves like a modern chat client, with features including:
- Group chats
- Stickers
- File sharing
- Read receipts
- Disappearing messages
But instead of routing everything through a proprietary company server, it works over standard email protocols (IMAP and SMTP) with automatic end-to-end encryption layered on top via the Autocrypt standard. In practice, that means your "account" can be an email address you already own, or a lightweight purpose-built "chatmail" address created just for chatting (no traditional inbox required), obtained from one of several independent chatmail relay providers.
Because it's built on an open protocol rather than a closed one, a Delta Chat user can, in principle, message any other Delta Chat user regardless of which email or chatmail provider each of them uses — nobody has to be on the same company's servers. Clients are available for:
- iOS
- Android
- Windows
- macOS
- Linux
- Ubuntu Touch
All of them are open source.
Who's behind it
Delta Chat is developed by a distributed group of contributors whose funding is coordinated by merlinux GmbH, a company based in Freiburg, Germany. According to the project's own help pages, funding has come from public and EU sources, plus individual donations:
- The EU's Next Generation Internet (NGI) programme
- The Open Technology Fund
- NLnet
- The EU-funded NEXTLEAP project
The project states plainly that it "does not receive any Venture Capital and is not indebted" to produce profit or monetise user data, which is a meaningfully different funding model from most chat apps.
Who should use it
Great fit if…
- You like the idea of a chat app that isn't tied to any single company's continued existence — because the underlying transport is email, your conversations and account aren't trapped inside one vendor's infrastructure.
- You're a tech-comfortable user, or part of a small organisation or community that wants to self-host or choose its own chatmail provider.
- You already rely on email and want encrypted, chat-style conversations layered on top, without adopting yet another proprietary account system.
Skip it if…
- You want built-in voice or video calling in the same app.
- You'd find "your chat account is an email address" a confusing concept rather than a feature.
Pricing in detail
Delta Chat itself has no price: the client apps are free and open source on every platform, funded by the grants and donations described above rather than by charging users or selling data. There is no premium tier inside the app itself.
The one place a cost can appear is outside Delta Chat's own control: if you don't want to reuse an existing email address, you'll register a "chatmail" address with one of several independent relay providers, some of which are free community services and some of which may charge a small fee or ask for a donation to cover server costs — this is set by each individual relay operator, not by the Delta Chat project, and pricing for those third-party relays isn't standardised or published centrally. If you already have an email account (from any provider), you can use Delta Chat with it at no additional cost at all.
Where it falls short
- No voice or video calling — the biggest functional gap: Delta Chat is a text-and-media chat app, so it won't replace a video-calling tool.
- Delivery speed and reliability depend on the email or chatmail server behind each side of the conversation, rather than a single dedicated low-latency network, so performance can vary more than with apps built on their own infrastructure from day one.
- The "your account is an email address" model is less intuitive to newcomers than typing in a phone number — getting non-technical contacts set up with their first chatmail address takes a short explanation.
- Support is community- and volunteer-driven — active documentation and a responsive open-source community, but no dedicated customer support line.
Privacy & data
Messages are end-to-end encrypted automatically between two Delta Chat clients using the Autocrypt standard, without users needing to manually exchange keys. Because the transport layer is email, some metadata (who's emailing whom, when) travels the way email metadata normally does, which is a different privacy profile from apps built entirely on a dedicated encrypted-messaging network — worth knowing if your threat model is specifically about hiding metadata rather than message content.
The project's funding disclosures are unusually transparent for a messaging app, publicly listing each grant source, which lets you check for yourself who has funded the software you're relying on.
How we checked this
We confirmed the funding and governance structure directly from Delta Chat's own help pages, which name merlinux GmbH (Freiburg, Germany) as the coordinator of contributor funding and list its EU/public grant sources, and state explicitly that the project takes no venture capital. We also confirmed the app is free with no in-app paid tier, and that any cost for a dedicated chatmail address is set independently by third-party relay operators rather than by the Delta Chat project itself.