logo Whisper! 
This software is functional but still under development and testing. Use at your own risk. Want something like this with your company branding, custom hosting, key synchronisation and more features? Get in touch!

D'Oh!

Sorry, this browser does not seem to support Web Cryptography API and the P-256 elliptic curve.
 

Welcome

Welcome! In order to securely send files, please provide one or more recipient. Nice! Now please add one or more files to be encrypted. Great! You're all set to encrypt some secrets. Congrats! You successfully encrypted your data.

To whom do you want to whisper?

Drag & Drop your recipient key(s) or click to open file chooser

What do you want to whisper?

Drag & Drop your file(s) to be encrypted or click to open file chooser

Ready?

Your data will be encrypted locally on your device and can only be decrypted by the chosen recipients!

Go!
Reset

Complete!

You can now download the encrypted files and send them to

Clear
 

Welcome

Welcome! In order to decrypt prviously encrypted data that has been sent sent to you, please drop at least one file into the box. Nice! Now you and only you can decrypt the content using your locally stored private key. Great! The files have been decrypted and can be downloaded.

What have you received?

Drag & Drop your file(s) to be encrypted or click to open file chooser

Ready?

Your data will be decrypted locally on your device and is never transmitted to any server!

Go!
Reset

Complete!

You can download the decrypted files here!

Clear

What can Whisper! do?

You can either head over to the Send section to encrypt something for somebody who has given you their Whisper! public key.

Or you use the Receive section to decrypt previously encrypted data sent to you. To receive a file that can only be decrypted by you, hand your current Whisper! public key to the sender(s).

Your keys

We have successfully created a keypair for you and stored it in your local browser! You can download the Whisper! public key here. It is not a secret and can be sent to anyone you wish to receive whispers from.

Please note, that if you clear your browser data for this site, existing keys will be lost and new keys will be generated. This is by design, so please ensure that senders have your latest Whisper! public key file.

Before downloading and distributing your key, please provide some info on who you might be, like Name or E-Mail to help senders using it.



Throw keys away

Data encrypted with this key pair cannot be decrypted again and once deleted the keys cannot be recovered.

Are you sure?

Yes
No

About Whisper!

Whisper! was created by Syncorix in order to securely exchange sensitive data with others. It runs in your browser and does not transmit any data to us. In order to make it available on the internet, it needs to be hosted. We chose our hosters with regard to privacy.
Please also see

How does Whisper! work

how does it work
This is quite simple: Whisper! uses asymmetric cryptography and the Web Crypto API to create two keys. One can be used for encryption and the other for decryption. The latter should not leave your browser's local storage. To exchange sensitive data the following steps are executed:
  1. The recipients send their public key parts to the sender and use whatever communication channel they see fit.
  2. The sender uses the key parts of all intended recipients, encrypts the data locally in the browser and sends the resulting cryptogram to the recipients.
  3. The recipients decrypt the cryptogram locally in their browser and save the sensitive data. They may throw away their keys rendering the cryptogram useless.
Thus the sensitive data never leaves the senders' and recipients' devices.

Security of Transmission

Encryption Strength

Whisper! uses JWE with strong encryption algorithms (e.g. AES-256-GCM for content encryption and P-256 Elliptic Curve for keys). These algorithms ensure that the payload remains confidential and tamper-proof.

Hybrid Encryption

JWE employs hybrid encryption, where:
  • A symmetric Content Encryption Key (CEK) is generated for encrypting the payload.
  • The CEK is encrypted for each recipient using their public key (asymmetric encryption).
  • This ensures that only recipients with the corresponding private key can decrypt the CEK and access the payload.

Integrity Protection

JWE includes an authentication tag (e.g. in AES-GCM) to ensure that the ciphertext has not been tampered with during transmission.

Conclusion

JWE is a highly secure mechanism for transmitting sensitive data over insecure channels, provided that:
  • Private keys are kept confidential.
  • Strong algorithms (like ECDH-ES+A256KW for key wrapping and A256GCM for content encryption) are used.
  • Libraries are kept up to date to mitigate known vulnerabilities.

License: whisper-ui (this software) 

MIT License

Copyright (c) 2025 Syncorix GmbH (syncorix.com)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

License: jose 

The MIT License (MIT)

Copyright (c) 2018 Filip Skokan

Permission is hereby granted, free of charge, to any person obtaining a copy of this
software and associated documentation files (the "Software"), to deal in the Software
without restriction, including without limitation the rights to use, copy, modify,
merge,
publish, distribute, sublicense, and/or sell copies of the Software, and to permit
persons
to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE
FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.

License: pure 

Software License Agreement (BSD License)
========================================

Copyright 2013 Yahoo! Inc.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above copyright
        notice, this list of conditions and the following disclaimer in the
        documentation and/or other materials provided with the distribution.

    * Neither the name of the Yahoo! Inc. nor the
        names of its contributors may be used to endorse or promote products
        derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL YAHOO! INC. BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

License: Material Design Icons 

Pictogrammers Free License
--------------------------

This icon collection is released as free, open source, and GPL friendly by
the [Pictogrammers](http://pictogrammers.com/) icon group. You may use it
for commercial projects, open source projects, or anything really.

# Icons: Apache 2.0 (https://www.apache.org/licenses/LICENSE-2.0)
Some of the icons are redistributed under the Apache 2.0 license. All other
icons are either redistributed under their respective licenses or are
distributed under the Apache 2.0 license.

# Fonts: Apache 2.0 (https://www.apache.org/licenses/LICENSE-2.0)
All web and desktop fonts are distributed under the Apache 2.0 license. Web
and desktop fonts contain some icons that are redistributed under the Apache
2.0 license. All other icons are either redistributed under their respective
licenses or are distributed under the Apache 2.0 license.

# Code: MIT (https://opensource.org/licenses/MIT)
The MIT license applies to all non-font and non-icon files.

License: Alpine.js 

# MIT License

Copyright © 2019-2021 Caleb Porzio and contributors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.