Cryptpad
CryptPad is a private-by-design alternative to popular office tools and cloud services. All the content stored on CryptPad is encrypted before being sent, which means nobody can access your data unless you give them the keys. CryptPad is a suite of zero knowledge, realtime collaborative editors and applications. Encryption carried out in your web browser protects the data from the server, the cloud, and the NSA. The secret encryption key is stored in the URL fragment identifier which is never sent to the server but is available to javascript so by sharing the URL, you give authorization to others who want to participate. CryptPad uses a variant of the Operational transformation algorithm which is able to find distributed consensus using a Nakamoto Blockchain, a construct popularized by Bitcoin. This way the algorithm can avoid the need for a central server to resolve Operational Transform Edit Conflicts and without the need for resolving conflicts, the server can be kept unaware of the content which is being edited on the pad. Cryptpad offers collaboration on text and WYSIWYG documents, as well as a basic polling application where users see results in real time.
