System Design: Google Docs

Design a shared document editor that lets people type locally while exchanging concurrent changes. The main challenge is preserving meaningful edits when collaborators are looking at different revisions, then recovering that state after a disconnect or server failure.

Problem statement

Collaborating on documents by exchanging files is inefficient. For example, if two users edit local copies of the same document simultaneously, merging their changes becomes a manual and error-prone process. The lack of synchronization often results in version conflicts and duplicated effort.

A collaborative service automates this exchange, but still needs explicit rules for concurrent edits, version history, and permissions.

Google Docs