Ever wondered how to create your own shared document service similar to Google Docs or Sheets? Then, in this blog, I'm going to introduce you to WOPI (Web Application Open Platform Interface) and walk you through its most popular applications.

What is WOPI?

WOPI is an open protocol defining how web applications integrate with online document editors. It enables seamless embedding of Office document viewing and editing directly in-browser, with the host application remaining the authoritative system for file storage and permissions.

Practically, WOPI eliminates the download-edit-upload workflow. Documents are edited in-place via tokenised API endpoints, with the host application maintaining control over file permissions, access rights, and data integrity across the entire editing lifecycle.

How It works in practice

When users open documents for editing:

  1. The application backend generates a secure WOPI source reference with time-bound access token
  2. This reference launches the office editor within an embedded iframe
  3. User edits occur directly in-browser
  4. Changes stream back through tokenised API endpoints to application storage
  5. The editor remains stateless, retaining no file access post-session

Microsoft 365 - The Official WOPI Client - and owner of the protocol itself. The integration itself is free, but it requires a lengthy and bureaucratic approval from Microsoft, ensuring all security and compliance criteria for hosting their product are met. Also, the end user needs to have an active Microsoft 365 subscription to be able to edit the files (even if it is not hosted in Microsoft), otherwise there is read-only permission granted.

ONLYOFFICE - Another popular application using WOPI is ONLYOFFICE, a modern Office-compatible suite with excellent Microsoft file format support. It is easily deployable via a simple Docker container or has installation instructions for all major operating systems. Community edition is free but limited to ~200 concurrent connections, making it not suitable for high-traffic/usage applications; Enterprise edition removes limits with commercial support and advanced features, but it is, in general, an expensive option - especially for more concurrent connections requirements.

Collabora Online - The last one for this article is Collabora Online, which is a production-grade LibreOffice-based WOPI client with unlimited scaling (hardware-limited). Deploys as a Docker container offering both free and commercial Enterprise versions. Requires a custom WOPI host implementation for interacting with the backend.