How to send a file securely without creating another attachment archive

Choose the channel by what must happen afterward

Use durable cloud storage or an approved document portal when the recipient needs reliable later access, version history, an audit trail, or an organizational record. Use a purpose-built, independently reviewed system when regulation or a high-risk threat model requires it.

A disposable room fits a narrower job: two known participants are online, one needs to transfer a file now, and neither wants the relay to become a permanent file archive.

How Babili transfers a file

1. Create a room and share its single-use invite with the intended recipient.
2. Keep both browsers connected, then attach a file up to 25 MiB.
3. The recipient explicitly requests the offered file.
4. The sender splits it into 64 KiB chunks and encrypts each chunk in the browser before sending it through the relay.
5. The recipient decrypts and reassembles the chunks locally, then chooses whether to save the file.
6. Destroy the room when the handoff and any clarification are complete.

The Cloudflare relay handles ciphertext and does not persist the file as a server-side attachment. The sender must remain connected because Babili is a live transfer, not an asynchronous file locker.

What room destruction does—and does not—remove

Destroying the room ends its server-side lifecycle and prevents Babili from becoming a durable transcript or file repository. It does not erase a file the recipient saved, copied, photographed, backed up, or forwarded, and it cannot clean clipboard history, browser downloads, notification previews, or a compromised endpoint.

The relay can still observe ordinary metadata such as IP addresses, connection timing, presence, and encrypted payload sizes. File-event authentication and sender identity verification are not implemented yet, and Babili has not completed an independent security audit. Do not treat it as an anonymous drop box, a compliance product, or a high-risk document-submission system.

A safer one-time handoff checklist

• Verify the recipient through a separate known channel when identity matters.
• Share only the minimum file needed for the task.
• Remove unnecessary document metadata before sending when appropriate.
• Keep your own required record in the system designed to hold it.
• Destroy the room after delivery, and assume the recipient can retain what they receive.