The Complete Guide to One-Time Messages (OTM): When, Why & How to Use Them

One-time messages ("OTM links") are one of the most powerful privacy tools on the internet — and one of the most underused.

This guide explains:

• when to use OTM
• why they're safer than chats
• how they eliminate screenshots, backups, and metadata
• real-world examples where they shine

What Is a One-Time Message?

An OTM link:

1. is encrypted locally with AES-256-GCM
2. can be opened exactly once
3. deletes itself instantly after being read
4. auto-expires after 7 days if unused

No metadata. No history. No identity.

Why OTM Links Are Significantly Safer Than Normal Messaging Apps

Normal chat apps store:

• metadata
• timestamps
• device fingerprints
• account IDs
• cloud backups

Even if content is encrypted, metadata is not.

OTM on zkChat stores:

• nothing
• no metadata
• no identity
• no history

The server only sees unreadable ciphertext.

When to Use OTM (Real Examples)

1. Sharing passwords or login credentials

Most common use case worldwide.

OTM — once opened — gone forever.

2. Sharing crypto seed phrases or private keys

Never paste seeds into any social messenger. OTM is the safest option.

3. Sending confidential business documents

Use cases:

• pitch decks
• investor spreadsheets
• tokenomics files
• design screenshots

OTM eliminates risk.

4. Sharing legal or medical information

Highly sensitive files need a one-time-only view.

5. Sending private photos securely

OTM is basically "self-destruct media".

6. Sharing access codes, WiFi passwords, alarm codes

Quick, clean, no trace.

7. Emotional messages you don't want stored

Breakups, confessions, apologies — all ephemeral.

8. Laptop to Phone transfer without cloud accounts

Private File Drop + QR code popup.

How OTM Prevents Leaks

• No history
• No screenshots synced to cloud
• No multi-open replay
• No metadata storage
• Automatic deletion

How OTM Works Technically

Sender:
- Encrypts message in browser
- Uploads ciphertext
- Gets link: /otm/<id>#key=<key>

Receiver:
- Opens link
- Server returns ciphertext once
- Immediately deletes stored data
- Browser decrypts locally

Zero-knowledge.

Common Questions

Q: What happens if I reload the OTM page?

A: The message is already consumed. It can only be opened once.

Q: Can someone screenshot it?

A: Technically yes, but there's no cloud sync or backup. The data never existed on a server in plaintext.

Q: What if I lose the link?

A: If the key fragment (#key=...) is missing or lost, the message is unrecoverable. That's by design.

Conclusion

OTM is what all "disappearing message" features should have been:

• truly one-time
• truly ephemeral
• truly zero-knowledge

Use it anytime you need to share something sensitive without leaving a trace.