Btwinus vs ChatCrypt: which one should you use for a private chat?
ChatCrypt and Btwinus look alike from the outside: open a page, no account, type, talk, close the tab, nothing kept. The difference is underneath. ChatCrypt relays every message through its server and lets a whole room in. Btwinus connects two browsers directly and lets nobody else in. That one choice decides almost everything.
If you've searched for "encrypted chat room no sign up", you've seen both of these. They're both free, both browser-only, both proud of keeping no logs. This post is about the parts the landing pages don't put side by side.
What ChatCrypt is
ChatCrypt is a long-running hobby project by a single developer. You fill in three fields, a nickname, a room name, and a room password, and connect. Anyone who knows the same room name and password lands in the same room and can read the conversation. That makes it a group tool by default, which is unusual among no-account chat sites.
Architecturally it's a relay. Your browser opens a WebSocket (over TLS) to ChatCrypt's server, and messages pass through that server to the other members. On top of TLS, ChatCrypt describes two more layers: an ECDH key exchange with AES-256 between each client and the server, and an end-to-end layer between members using ChaCha20-Poly1305, with the keys mixed with the room password so that, in their words, the server can't reconstruct them. The site says nothing is stored: no database, no logs, no history.
A few things worth knowing. The source code isn't public, the site says it may share it "if given a well-founded request", such as a security audit, which is not the same as being open source. The service is ad-funded, loading Google AdSense and other ad networks with personalised-ads consent prompts. We didn't find file sharing or voice; reviews going back years describe it as text only, and the copyright notice we saw was dated 2023. A 2014 public disclosure criticised the site for serving its crypto JavaScript over plain HTTP; it now uses TLS. And because the whole model rests on a room password, anyone who guesses or is given that password is simply in.
What Btwinus is
Btwinus is a one-to-one chat with no server between the two browsers. You click "Start a new chat" and get an invite link and a passphrase. The link's URL fragment holds a WebRTC offer encrypted with AES-256-GCM, the key derived from the passphrase by PBKDF2 (100,000 iterations). You send the link through one channel and the passphrase through another. The other person opens the link, types the passphrase, gets a reply link, and sends it back; you paste it, and the two browsers connect directly over WebRTC. From there, messages travel peer to peer. Close either tab and the conversation is gone.
Both sides see a short authentication string to compare out loud, which catches anyone who tried to sit in the middle of the handshake. Btwinus is free, has no ads, and is open source, a static page you can read in an afternoon or host yourself. (Here's how the link carries the encryption.)
What it doesn't do: groups, files, or asynchronous messages. Exactly two people, both online at once, text only.
The honest comparison table
| Property | ChatCrypt | Btwinus |
|---|---|---|
| Account required | None | None |
| Transport | Relayed through ChatCrypt's server (WebSocket) | Direct browser to browser (WebRTC) |
| Server sees metadata | Yes, who connected, when, which room | No server in the chat path |
| Content encryption | End-to-end layer (ChaCha20-Poly1305) over ECDH/AES-256 to server, over TLS | AES-256-GCM handshake, then WebRTC's DTLS between peers |
| Secret that gates entry | Room name + room password | Link + passphrase, sent on separate channels |
| Handshake verification | None shown to users | Short authentication string on both sides |
| Group chat | Yes | No, one to one |
| Both online at once | Yes (no history) | Yes |
| Files | No | No |
| Message history | None claimed | None by construction |
| Open source | No (source on request) | Yes |
| Self-hostable | No | Yes, static files |
| Ads | Yes | None |
| Cost | Free | Free |
Where ChatCrypt is the better choice
More than two people. This is the decisive one. A team huddle, three friends coordinating, a small community that wants a throwaway room, ChatCrypt does it, Btwinus flatly does not. If you need a group, stop reading and go there (or to Signal).
Joining is dead simple. Tell people a room name and a password, and they type it in. No links flying back and forth, no reply link to paste. For a non-technical crowd that's real friction saved.
Late arrivals. Someone can join a ChatCrypt room ten minutes after it started (they won't see earlier messages, but they're in). A Btwinus session is fixed at two from the handshake onward.
Awkward networks. Because ChatCrypt relays through a server, it works anywhere a WebSocket works. WebRTC peer connections occasionally fail behind restrictive corporate firewalls or symmetric NATs, and Btwinus has no relay to fall back on.
Where Btwinus is the better choice
No middleman at all. Every ChatCrypt message passes through one server, and that server sees connection metadata, IPs, timing, room names, even if it truly can't read content. Btwinus has no server in the conversation; the only thing a static host ever sees is a request for an HTML page.
Room passwords are a single secret; Btwinus uses two. In ChatCrypt, whoever has the room name and password is in, and both usually travel together in the same message. Btwinus separates the link from the passphrase across two channels, so one compromised channel isn't enough. (That split is the point of how to share a password without leaving a copy behind.)
You can check who's on the other end. The short authentication string exists to catch a man in the middle. ChatCrypt gives you no way to tell whether the "other member" is who you think.
You can read the code. ChatCrypt's security claims are detailed and plausible, but unverifiable unless you're granted the source. Btwinus is public, small, and uses only the browser's built-in Web Crypto and WebRTC.
No ad networks in a "private" chat. Loading AdSense and consent banners into a page that exists to be private is a contradiction Btwinus doesn't have.
How to decide
- Three or more people → ChatCrypt (or Signal for anything ongoing).
- Exactly two people, and it matters → Btwinus.
- You can't tolerate any server seeing that the conversation happened → Btwinus.
- Recipients who'll struggle with a link-and-passphrase dance → ChatCrypt.
- You want to audit what you're trusting → Btwinus.
- Files, history, offline delivery → neither.
ChatCrypt is a shared room with a bouncer who can't hear you but knows you came. Btwinus is a private line with no building around it. Pick by headcount first, and by who you're willing to trust second.
Just two of you? Skip the relay and connect directly.
Start a private chat →