Google Docs

Google Docs is a browser-based document editor where multiple people can write in the same file simultaneously, with every change saved and attributable.

Its version history is more useful than most people realize: you can see who changed what and when, and restore any earlier state — which makes it a reasonable audit trail for collaborative work.

Formatting fidelity when exporting to Word is imperfect for complex layouts, so documents going to external parties in .docx are worth checking before sending.