Help:Extension:ParserMigration

The ParserMigration extension allows users to compare the output of the legacy wikitext parser with the latest Parsoid wikitext parser.

Enabling via user preference
This extension adds Enable parser migration tool and Use Parsoid by default to the list of Developer tools options at the bottom of the Editing preferences for a user. To opt-in to test Parsoid read views, ensure Use Parsoid by default is checked.

Opting in to Parsoid read views on all wikis
To opt in to Parsoid read views on all wikis, you will need to select Use Parsoid by default in your global preferences. First, click the Set your global preferences button on the "User profile" page of your user preferences: After you have switched to global preferences, select the Enable parser migration tool and Use Parsoid by default options at the bottom of your Editing preferences tab:

Switching between Parsoid and the legacy parser
When Use Parsoid by default is selected, article and discussion pages will use the new Parsoid parser by default. To compare the output to the legacy parser, or to temporarily switch back to the legacy parser, a link is added to the user tools sidebar.

Comparing article rendering
When Use parser migration tool is enabled, an Edit with migration tool link is added to the Tools menu in the sidebar for article pages. Clicking this on an article page will bring up a variant of the "preview edit" page which allows you to compare the legacy parser output against Parsoid output.

Action API
This extension also adds  to the MediaWiki action API, which parses a page with two different parser configurations and returns one or both variants in the API response.