Peer-to-peer, even in groups
In a voice room, the member with the best connection becomes the host and passes the already-encrypted audio on to everyone else. If they leave, a backup takes over within moments.
Voice and text chat, peer-to-peer
Talk freely.
Nobody in between.
Spaces with text channels and voice rooms, DMs and calls, like the apps you know. The difference is underneath: what you say goes straight to the people you're talking to, end-to-end encrypted with post-quantum keys. No company server stores it or can read it, and there's no phone number, email or password to hand over.
Free and open source · Windows, macOS and Linux · Public beta
- 0servers that can read your messages
- 0phone numbers, emails or passwords
- 1 keyper message: each one is encrypted with a fresh key
- PQpost-quantum key exchange, everywhere
What's new
A chat app with no middleman
Most messengers send everything through their company's data centres, even when it's encrypted. Crocodile has no data centre in the middle: your apps talk to each other.
An account that is a key
Pick a name and you're in. Your identity is a key made on your device, and your user ID is derived from it, so no server can give your name to someone else. There's no password to phish and no password database to leak.
Quantum-safe today
Every key exchange combines classic X25519 with ML-KEM-768, the post-quantum standard NIST published in 2024. Traffic recorded today stays private even if quantum computers break classic cryptography later.
Servers anyone can run
Coordination servers only introduce people. Anyone can run one, from a rented server or a single switch in the app, and they all join one shared network. Crocodile doesn't depend on us.
Familiar on the surface
Everything where you'd expect it
If you've used a chat app for communities, you already know your way around. Light and dark themes come built in.
Features
Everything you need to hang out
Spaces for your people
Text channels and voice rooms for your friends, your guild or your whole community, with admins, invite links and bans. Invite links show up in chat as cards you can join with one click.
Rooms you can see into
See who's inside before you join, who's talking, and how good everyone's connection is, live.
Calls and DMs
Call a friend in one click. It rings, you answer, you hang up, and both of you always see whether the call is really live.
Push-to-talk, even in a game
A system-wide push-to-talk key works while another app is in front, mouse side buttons included.
Messages that wait for you
Wrote while a friend was offline? The message waits on your device and goes out the moment you're both online. If you like, a server can hold it for up to a week, sealed so only your friend's devices can open it.
All your computers
Add a laptop by typing a short code and checking that both screens show the same security number.
Chat that feels modern
Mentions, emoji, clickable links, replies, edits and code blocks, plus sounds for calls and messages.
Make it yours
Light and dark themes, your own accent colour, and a command palette to get anywhere fast.
How it works
Three steps, no middleman
-
1
Find a server
Your app gets the list of coordination servers, connects to the fastest and keeps the runner-up on standby.
-
2
Meet your people
The server tells your app who's online and which member is best placed to host. It sees who talks to whom, never what is said.
-
3
Talk directly
Your app connects to the host, or straight to your friend, and everything flows app to app, encrypted end to end.
How it compares
Next to the apps you know
The headline differences. The full table explains every cell and links to its source.
| Crocodile | Signal | Telegram | Discord | TeamSpeak | ||
|---|---|---|---|---|---|---|
| Sign up without a phone number or email | ||||||
| Messages end-to-end encrypted by default, groups too | ||||||
| Voice end-to-end encrypted, groups too | ||||||
| Post-quantum key exchange | ||||||
| Voice and messages go app to app, not through company servers | ||||||
| Run your own server |
Security
Security you can check
Strong encryption is only worth something if you don't have to take it on trust. Everything about Crocodile's design is public.
- Open source. Every line of the apps and servers is on GitHub for anyone to read and build.
- Signed, not trusted. Profiles, spaces, invites and memberships are signed by their authors and checked by every app, so a server can't forge them.
- Keys that move on. Every message gets a new key, voice keys change every 30 seconds, and fresh keys replace them every 30 minutes and whenever someone leaves.
- Little left to analyse. Voice runs at a constant bitrate and messages are padded, so packet sizes don't give away what you said.
- Honest about limits. Crocodile hasn't had an independent security audit yet. Until it has, don't rely on it where your safety depends on it.
From the creator
Hi, I’m Paweł Walda (@pwalda), and I created Crocodile.
I built it with a lot of help from GenAI, and I won’t pretend otherwise: written entirely by hand, it would have taken years instead of months.
But the idea, the vision and the principles are my own and all organic, and so are the many days I’ve put into it.
The protocol is what I am proud of the most, as it is made of the most basic elements combined in a way that makes it a novelty, something that came directly from my brain. So I can call myself a semi-inventor 😉
I don’t ask you to take it on trust. Everything is open source and open to the public. I invite you to work with me on this project: to audit it, to patch any bug, and to report any vulnerability if you find one.
My ultimate goal is not just to create another secure communicator; there are plenty of those. I don’t want it to be an obscure app used only by advanced users, but one that gamers and regular people use in their daily communication. I know it’s a long way, but at the end of the day it’s free, it’s secure and it’s open source. What else do you need?
Why do this at all? Because I believe everyone has the right to talk to each other directly, safely and privately, with nobody listening in.
And I think I am not the only one…
Ready when you are
Free, open source and quick to set up: install, pick a name, invite your friends.
Questions
Is it free?
Yes. Crocodile is free and open source, and talking and privacy will stay free. If you'd like to help pay for the servers and development, you can support it.
What does “beta” mean here?
Crocodile works, but expect rough edges, and please tell us about them. The encryption design is public and the code is open, but it hasn't had an independent security audit yet. Until it has, don't rely on it where your safety depends on it.
Can the servers read my messages?
No. Messages and voice never pass through coordination servers, except when you turn on the relay or the mailbox, and even then they stay end-to-end encrypted and unreadable to the server. Servers do see profiles and who talks to whom; the security page and our privacy notice list exactly what.
If servers can't read anything, what are they for?
Introductions. They tell your app who's online, help apps find a way to reach each other through home routers, and decide which member hosts a voice room. Think of them as a switchboard that connects calls but never listens in.
What happens if my friend is offline?
Your message waits on your device and is delivered as soon as you're both online. If you turn on the mailbox, a server holds it for up to a week, sealed so only your friend's devices can open it.
How do I use it on more than one computer?
On the new computer choose I already use Crocodile → Link from another device, type the code it shows into a computer where you're signed in, and check that both show the same security code.
What if I lose all my devices?
When you create your account, Crocodile shows you a recovery key. Keep it somewhere safe: with it you can restore your account on a new computer. Without it, nobody can, us included, because there's no password reset and no copy of your key on any server.
How do I delete my account?
In the app, Settings → Profile → Delete account. It's erased from the coordination servers and signed out on all your devices. Spaces you own are deleted for everyone.
Is there a phone or web version?
Not yet. Crocodile runs on Windows, macOS and Linux today; phones come later.
Support Crocodile
Crocodile has no ads, no tracking and no paid features. Donations pay for the main server and development. They're gifts: everyone gets the same app whether they give or not.