The diff editor extension shows the diff between the draft value and the published value of a short text field.
Check you have the requirements needed to use extensions.
Start a local server, changing the port if needed:
python -m SimpleHTTPServer 3030
Don't use the extension.json
descriptor file but instead use 3rd party hosting from localhost
contentful extension update --force --src 'http://localhost:3030/index.html' --id diff --name diff --field-types Symbol -field-types Text
The same constraints apply to loading unsafe scripts.
Enable the extension in the Contentful web app for a "Short text" field by opening the Settings for a field and selecting the widget in the appearance tab.