Anonymous Chat AI (AChat)

Open the page, copy the URL, send it. That is the whole setup.

AChat asks for no email, no account and no install. You pick a chat identifier or let the page generate one, and whoever opens the link you send them is in the room with you.

That is the easy half.

The difficult half is the word private, which most chat products use to mean that somebody somewhere has written a policy about it. Here it means a key that never leaves your browser.

Add a password and the room changes.

The password derives a key with PBKDF2 and messages are sealed with AES-GCM through the Web Crypto API. The server holds ciphertext it has no way to open.

It also means there is no recovery.

Lose the password and the conversation is gone, because any route back into it would be a copy of the key held by somebody who is not in the conversation. That trade is the feature working.

The room dies with it.

Rooms expire on their own as well. A Firestore time-to-live policy deletes the whole thing after 10 days, which is deletion on a timer rather than an archive nobody reads.

Very little is left to protect by the eleventh day.

Under a deliberately plain surface there is more product than the first screen suggests. The composer is TipTap, carrying slash commands, mentions, emoji, reactions, quote-reply, voice memos and code highlighting.

Files ride through FilesHub at up to 10 MB each.

They go through a multi-file upload queue with retry, so one bad connection loses one file rather than the batch. Search across a room is fuzzy, because nobody recalls the exact words they used two hours ago.

There is a lightbox for images and an embeddable iframe widget for putting a room inside another site, which turns a support conversation into a few lines of markup on somebody else's page.

A PWA service worker is registered, and the whole interface sits behind a Radix theme customiser with accessibility modes. Those modes are not decoration on a product whose entire job is a conversation somebody needs to read.

None of that is visible on the first screen, and that is intentional. A product whose selling point is that it asks you for nothing should not open by showing you everything it can do.

The constraint behind all of it is Firebase's free Spark plan.

There is no paid backend anywhere in the room, which is why a room can cost nothing to leave running and nobody has to justify keeping it alive. Zero infrastructure cost is what lets one person keep a long list of things running at the same time.

That constraint also shapes the cryptography.

A server that cannot read a message is a server that needs no expensive protection around what it stores, and the cheapest data to secure is data you never held in the clear.

What it cost is retrieval.

Everything convenient about a normal chat product comes from the server being able to read the messages: search across the whole history, account recovery, moderation, an export somebody can be sent months later, and a password-protected AChat room gives every one of them up, because its plaintext exists only in the browsers of the people in it. That is the bill.

It is also in progress rather than finished, which belongs on the page and not in a footnote.

It is at achat.aoneahsan.com, and the Android build is on Google Play.

There is no way to get a room back once the password is gone, and that is the feature rather than a defect in it.