CRDTs / Local-First
Also written as CRDT, Conflict-Free Replicated Data Type, Local-First, Local-First Software, Yjs, Automerge
A way of storing shared data so several people or devices can edit it at the same time, even offline, and every copy automatically ends up identical without a central server settling conflicts. One of the main techniques behind live multi-user editing in collaborative apps. Yjs and Automerge are popular libraries, and 'local-first' apps are built on the idea.
Think of it like
Several people editing their own copies of a shared shopping list that always merge into the same final list, whatever order the changes arrive in.
Junior or senior?
Hard, specialised and highly differentiating; closely related to offline-first mobile work.
Senior sounds like
Has shipped real-time collaboration and can talk about memory growth, undo and permissions.
Ask them
“What happened when two people edited the same thing at once, and what did the merged result look like to them?”