Why we built zkChat: True privacy requires zero knowledge

Most messengers today pitch "privacy" as a feature. End-to-end encryption, disappearing messages, private mode.

But in reality, there is almost always someone in the middle who could see something:

• Servers that store metadata forever
• Cloud backups that silently re-upload your chats
• Companies that need analytics and growth dashboards
• Legal or political pressure to weaken encryption

I wanted something different: a tool that doesn't want to know who you are, who you talk to, or what you say.

That's why zkChat exists.

What zkChat actually is

zkChat is a set of zero-knowledge tools:

• Ephemeral group rooms – end-to-end encrypted chats that vanish when everyone leaves
• One-time messages (OTM) – links that can be opened exactly once, then self-destruct
• Private file drop – files are encrypted client-side and auto-expire

There are no accounts, no usernames, no profiles. Your "identity" in a room is just a local, random persona: a color and a fun name. Reload the page and even that changes.

Encryption in the browser, not on the server

All encryption happens on your device using AES-256-GCM:

• For each room or one-time message, the browser generates a 256-bit key
• That key never leaves your device in plaintext
• Messages or files are encrypted with that key before they ever hit the network

The decryption key is stored in the URL fragment (the part after #key=...). Browsers do not send that fragment to servers.

The server only ever sees:

• room IDs
• encrypted ciphertext blobs
• basic presence counts (how many sockets are connected)

It never sees:

• message content
• file content
• encryption keys
• usernames or identities

Even if you gave someone full access to the server, they would see only random bytes.

Why there's a donate button at all

Running zero-knowledge tools isn't free:

• Servers and bandwidth cost real money
• Abuse protection and rate limiting take time to build
• I want to keep zkChat independent: no ads, no trackers, no VC growth pressure

That's why there are crypto addresses in the footer and on this blog.

Donations keep zkChat:

• Ad-free
• Tracker-free
• Account-free

If zkChat is useful for you, consider it like tipping your favorite open-source project — it's what keeps the lights on without selling your data.