Ethercalc

Ethercalc is a wildly explosive, highly tactical open-source disruptor that mathematically attacked the "Zero-Setup Collaboration" market. It explicitly rejects user accounts, passwords, and massive enterprise deployments. It is the absolute weapon of choice for fast-moving hacker teams and anonymous collectives who mathematically demand to instantly generate a unique URL, share it in an encrypted chat, and have 50 people instantly co-editing a real-time spreadsheet grid without ever logging in.