Because of our encrypted architecture, Standard Notes does not currently provide a real-time collaboration solution. Multiple users can share the same account however, but editing at the same time may result in sync conflicts, which may result in the duplication of notes.
While collaboration is currently out of scope for us, it is an area we are keeping a close eye on. Providing end-to-end encrypted collaboration will require using client-side collaboration software, as opposed to server-side software which is used by popular collaboration tools today. Server side software requires the server to be able to parse and understand user content, which does not meet our security standards.
Client side collaboration is a nascent field, and we intend to monitor its progress for use in Standard Notes in the future.