Decentralized messenger that assigns no identifier to users, not even a random number. Contacts are established via one-time invite links or QR codes, with all data stored on-device only.
Official website simplex.chat
Our take
No other mainstream messenger can honestly say it collects zero metadata about who talks to whom, because every other app still ties you to a phone number, email, or account ID. SimpleX routes messages through relays without linking sender and recipient on the server side, and the protocol has been audited by Trail of Bits. The real trade-off is setup friction: sharing an invite link is awkward compared to searching a username, so getting less tech-savvy contacts onboard takes effort. For high-stakes private communication, that friction is worth it.
GitHub at a glance
simplex-chat/simplex-chat
Stars
11,283
+ 17 this week
Last commit
1d ago
healthy
License
AGPL-3.0
Latest release
v6.5.4
17d ago
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SimpleX Chat license, in plain English
AGPL-3.0 Strong copyleft · network
Free to use, even commercially. Changes must be published under the same license, and running a modified version as a network service counts as distributing it.
Permits
- Commercial use
- Modification
- Distribution
- Patent use
- Private use
Requires
- Disclose source
- Network use is distribution
- Same license
- State changes
- License and copyright notice
Does not provide
- Liability cover
- Warranty
Why it matters: The network clause is the point. Anyone who runs a modified version as a hosted service has to publish those changes, so the code handling your data stays inspectable. This is why privacy-first projects reach for AGPL.
Plain-language summary of the project's license, not legal advice. Read the full text for the exact terms.