SeeOnce Privacy

Tracking since Apr 1, 2026.

Changelog

• Jun 2, 2026
  description

  SeeOnce encrypts your email messages so they self-destruct after the recipient has read them. It does this without involving any servers or forcing you to make an account anywhere. You can keep using your preferred email.
  
  All other apps and extensions store your private content somewhere. SeeOnce does not do this; instead, it achieves forward secrecy by changing encryption keys with every message. This way, you don't have to trust anybody.
  
  When you get a locked message, just paste it into the extension and it will open automatically. Then you can reply directly from within the extension.
  
  Your friends don't need to have this extension. Messages open in a webpage just by clicking them. They can do this on an Android smartphone if necessary.
  
  Some people live in places where using encryption is itself compromising. This is why the extension can disguise its output so it looks like normal text. Just supply a sufficiently long cover text after the message is locked. Disguised messages also unlock as soon as you paste them in.
  
  If you find yourself exchanging a lot of emails, SeeOnce allows you to switch to real-time chat, which can involve text, files, audio, or even video. Just click the Chat button to make a secure invitation that only your correspondent can open, and then only once.
  
  Comprehensive help is just one click away.
  
  The extension uses 255-bit standard elliptic curves, which have been vetted against weaknesses by experts. On top of that, it uses 256-bit XSalsa20 encryption and 512-bit hash functions to complete the locking process. XSalsa20 is a high-performance, open source cipher, which has been scrutinized by experts for nearly a decade without any practical weaknesses being found.
  
  This is the Chrome extension version of SeeOnce, essentially identical to the web version, except that it syncs its data seamlessly between machines.
  
  The following is to check the authenticity of the web version:
  
  Current version is: 1.2.12
  Main source: https://PassLok.com/SeeOnce

  ⚠️ NOTICE: THIS EXTENSION HAS EVOLVED INTO PRIVACY BAR ⚠️
  
  This legacy standalone tool is no longer actively maintained. The exact same functionality has been integrated, upgraded, and fully secured inside our flagship extension: Privacy Bar.
  
  Looking for pure Symmetric Encryption? Privacy Bar handles it entirely offline.
  
  Looking for Read-Once payloads? Privacy Bar generates self-destructing messages out of the box just like SeeOnce, and can handle several recipients at once.
  
  Looking for Page Isolation/Sandboxing? Privacy Bar features an enhanced, isolated "Safe Space" tab.
  
  👉 Search the Chrome Web Store for "Privacy Bar" or visit privacybar.net to upgrade to the complete, modern suite.
  
  SeeOnce encrypts your email messages so they self-destruct after the recipient has read them. It does this without involving any servers or forcing you to make an account anywhere. You can keep using your preferred email.
  
  All other apps and extensions store your private content somewhere. SeeOnce does not do this; instead, it achieves forward secrecy by changing encryption keys with every message. This way, you don't have to trust anybody.
  
  When you get a locked message, just paste it into the extension and it will open automatically. Then you can reply directly from within the extension.
  
  Your friends don't need to have this extension. Messages open in a webpage just by clicking them. They can do this on an Android smartphone if necessary.
  
  Some people live in places where using encryption is itself compromising. This is why the extension can disguise its output so it looks like normal text. Just supply a sufficiently long cover text after the message is locked. Disguised messages also unlock as soon as you paste them in.
  
  If you find yourself exchanging a lot of emails, SeeOnce allows you to switch to real-time chat, which can involve text, files, audio, or even video. Just click the Chat button to make a secure invitation that only your correspondent can open, and then only once.
  
  Comprehensive help is just one click away.
  
  The extension uses 255-bit standard elliptic curves, which have been vetted against weaknesses by experts. On top of that, it uses 256-bit XSalsa20 encryption and 512-bit hash functions to complete the locking process. XSalsa20 is a high-performance, open source cipher, which has been scrutinized by experts for nearly a decade without any practical weaknesses being found.
  
  This is the Chrome extension version of SeeOnce, essentially identical to the web version, except that it syncs its data seamlessly between machines.
  
  The following is to check the authenticity of the web version:
  
  Current version is: 1.2.12
  Main source: https://PassLok.com/SeeOnce

Permissions & access

Permissions

storage

Host access

None declared

Screenshots

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