This section depends on the

Confidence Framework

to determine deployment readiness, and thus timings may change.

  • January/February 2026:
    • Deployed Parsoid Read Views to 69 additional wikis since Jan 1. As of February 26:
      • Parsoid is the default parser on 488 wikis (268 Wikipedias).
      • Parsoid is now serving ~10.5% of Wikipedia page views and ~1,725M total WMF monthly page views
      • 57M content pages (16.7% of total) are now rendered with Parsoid
    • Completed new test suite for LanguageConverter functionality with community validation from zhwiki
    • New LanguageConverter implementation now passes all parser tests including legacy Parser tests previously failing, and has been deployed experimentally to production.
    • Incremental roll-out feature deployed to top-50 wikis to gradually warm ParserCache, addressing critical blocker for enwiki deployment
    • Parsoid will be the default parser in a test adding a table of contents on mobile web, introducing about 0.1% of English Wikipedia readers to Parsoid Read Views.
  • March 2026:
    • Deployed Parsoid Read Views to 14 additional Wikipedias, reaching 502 wikis (283 Wikipedias) with ~20.1% Wikipedia page view coverage and ~2,972M monthly Wikipedia page views.
    • LanguageConverter patches merged and deployed to production; visual diff testing enabled for all 14 language converter wikis (4,583 articles tested).
    • FlaggedRevisions postprocessing cache support deployed, unblocking German and Russian Wikipedia deployment.
    • Parser cache hit rate improved from 69% to 75% through cache expiry optimizations.
    • QuickSurvey for Parsoid opt-out users deployed across multiple wikis after Legal privacy review cleared; results show 60% of users who disabled Parsoid didn't know what it was.
    • Responded to zhwiki edit corruption incident (Feb) caused by experiment misconfiguration exposing latent bugs; ~100 edits affected, emergency backport deployed within hours.
  • Deploy Parsoid to German, Spanish, French, and Russian Wikipedia — collectively representing ~20.3% of page views. German and Russian now unblocked by FlaggedRevisions support.
  • Complete deployment to remaining language variant wikis and remaining Wikipedias (excluding enwiki and zhwiki, separate milestone).
  • Complete the deployment to enwiki and zhwiki by the end of June
  • Parsoid enabled by default in MediaWiki by the next long-term support release, MW 1.47 in September 2026.
  • March 2026: Parsoid Read Views reached ~20.1% of Wikipedia page views across 502 wikis (283 Wikipedias), up from 10.5% at start of quarter. LanguageConverter patches merged and deployed to production; FlaggedRevisions support shipped, unblocking German and Russian Wikipedia; parser cache hit rate improved from 69% to 75%. QuickSurvey results showed most opt-out users were unaware of the migration. Next targets: dewiki, eswiki, frwiki, ruwiki (~20.3% additional page views).
  • February 2026: Responded to zhwiki edit corruption incident caused by experiment misconfiguration exposing three latent bugs (~100 edits affected); emergency backport deployed within hours with transparent community communication. Deployed Parsoid Read Views to 69 additional wikis since Jan 1, reaching 488 wikis (268 Wikipedias) with ~10.5% Wikipedia page view coverage. New LanguageConverter implementation now passes all parser tests; incremental roll-out feature deployed to top-50 wikis to address enwiki ParserCache warm-up blocker.
  • January 2026: Deployed Parsoid Read Views to 27 additional Wikipedias, reaching 445 wikis total (227 Wikipedias) with 9.0% Wikipedia page view coverage and 1,507M total WMF monthly page views (1,351M Wikipedia views). Completed new LanguageConverter test suite with bidirectional/unidirectional rule support and community validation from zhwiki, with patches passing all parser tests including legacy tests. Visual diff testing on top 100 most-read articles identified two actionable rendering bugs; incremental roll-out feature deployed to top-50 wikis to address enwiki ParserCache warm-up blocker.
  • December 2025: Successfully deployed Parsoid Read Views to Italian Wikipedia (itwiki) and Dutch Wikipedia (nlwiki)—the two "top-10" Wikipedia targets—substantially completing the work on cache infrastructure. Coverage doubled from 2.70% to 6.58% of Wikipedia page views, surpassing 1 billion total WMF monthly page views (986M on Wikipedia alone).
  • November 2025: Deployed Parsoid to 18 additional Wikipedias (160 total), with coverage nearly tripling from 1.02% to 2.69% of Wikipedia page views (403M monthly views, up from 110.8M). Achieved critical performance breakthrough with postprocessing pipeline optimizations reducing page processing time from ~4 seconds to ~2.2 seconds (50% improvement). Indonesian Wikipedia (idwiki, top-15 wiki) successfully deployed, validating readiness for high-traffic volumes. Prepared Italian and Dutch Wikipedias for December deployment as next major milestone toward top-ten coverage.
  • October 2025: Deployed Parsoid Read Views to 26 additional Wikipedias, expanding coverage to 355 wikis and 110.8M monthly Wikipedia page views. Continued visual diff testing and user report resolution, with work progressing on flavor cache and performance fixes.
  • September 2025: Total coverage to 329 wikis serving 9.9M monthly Wikipedia page views (~1.06% of WMF traffic). Process improvements included implementing weekly visual diff testing as part of the chore wheel, which identified unexpected low-hanging fruit and improved team knowledge sharing.
  • August 2025: Deployed to additional 58 small-size Wikipedias. Achieved significant performance improvements including 5% tokenizer speedup (17% cumulative improvement since April) and reduced Out Of Memory failures. Coverage reached 1.02% of all WMF page views, with itwiki and nlwiki identified as candidates for Q2 rollout; high confidence confirmed toward KR target.
  • July 2025: We have begun to deploy Parsoid Read Views to 70 low-page-view Wikipedias, in preparation for a larger deployment to Wikipedias later this fiscal year.
  • April - June 2025 - Performance focus: We worked to improve Parsoid's wikitext -> HTML performance to reduce the performance gaps between Parsoid and the legacy parser. There is some other work in progress, and additional work will be picked up on demand in later quarters.
  • April 2025: Parsoid read views deployed on most Wiktionaries, Incubator wiki, and Dagbani Wikipedia
  • February 2025: Parsoid read view roll out to Wiktionaries begins
  • Fall/Winter 2024:
    • Parsoid read views enabled by default on most wikivoyages.
    • → Project:Tech News
    • Parsoid read views enabled by default for talk pages on wikitech.
    • Parsoid read views enabled by default for main namespace and talk pages on officewiki.
  • November 2023:
    • Individual user opt-in to parsoid read views for articles was deployed as part of the ParserMigration extension.
  • July 2023:
  • Feb 2023:
  • Dec 2022:
  • Oct 2022:
  • Sept 2022:
  • July 2022:
    • Started work on adding i18n and l10n support in Parsoid.
    • (incomplete: to be updated)
  • 2022 (Jan - June):
    • Started evaluating Parsoid HTML against core HTML wrt size differences, and identifying what parts (tags, annotations, attributes) of Parsoid HTML to strip so that Parsoid-HTML read views don't have serious impacts on bandwidth and client rendering latencies. Acceptable divergences will be selected in conversations with the Performance team.
    • Started work on making Kartographer compatible with Parsoid.
    • Updated Graph to be compatible with Parsoid.
    • Updated MediaWiki core ParserTest runner to support running Parsoid tests in CI and development. This lets extensions (especially those that operate on wikitext) that target Parsoid to test their implementation via parser tests.
    • (incomplete: to be updated with changes in core repo and any other extensions)
  • 2021:
    • Make <translate> extension functional with Parsoid
    • A whole bunch of performance work to reduce wt2html transformation latencies
    • Switched a few wikis (testwiki, test2wiki, mediawikiwiki, officewiki, wikitech, group0) to use Parsoid-style HTML for media wikitext. Complete rollout to all wikis blocked on ironing out a number of other compatibility issues.
    • Experimental / prototyping work to switch to the Dodo DOM library from native PHP DOM -- project put on hold indefinitely after running into performance issues.
    • Lots of bug fixes and fixes to edge case incompatibilities between Parsoid and legacy parser.
    • (incomplete: to be updated with changes in core repo and any other extensions)
  • December 2020:
    • Finished addressing bulk of functionality differences between Parsoid and core version of Cite implementation
    • Fixed parsing differences between Parsoid and core in use of templates for table-cell attributes and the like
    • Started migrating core output for media wikitext to use Parsoid-style output to reduce output differences between Parsoid and core
    • Updated parsertests framework to enable extension implementations to be tested against Parsoid. Finishing this lets us move extension code out of Parsoid repository into the extension repositories and enables other extensions to start enabling support for Parsoid and run tests with Parsoid
    • Recalibrated our original plans to migrate all extensions to be Parsoid-compatible to a smaller subset. We will initially target only those extensions that implement tag hooks OR use parser hooks. Those that simply use public parser methods could continue to use the core parser for a while
  • November 2020:
    • Introduced uniform error handling for extensions with boilerplate code handled by Parsoid
    • Identified resource module related issues in Parsoid output that result in rendering differences between Parsoid and core output
    • Made ImageMap extension Parsoid-compatible
  • October 2020:
    • Several technical debt fixes ending in using a single document per request with document fragments for nested pipeline parses
    • Ongoing fixes to Parsoid's Cite implementation
    • Identify CSS fixes to reduce rendering differences between Parsoid and core output
    • Ongoing syncing and consultation with the Platform Engineering Team to upgrade the ParserCache infrastructure to accommodate Parsoid use cases and Parsoid clients in the future
  • September 2020:
    • We continued outreach about Parsoid's Extension API and get feedback (Emails on wikitech-l and mediawiki-l lists).
    • We have been continuing to fix functionality gaps between Parsoid's Cite implementation and the default Cite implementation.
  • August 2020:
    • We have been publishing results of weekly visual diff runs comparing Parsoid rendering and core parser rendering here.
    • We filed a TechCom RFC for Parsoid's Extension API. We also presented a Tech Talk about this.
    • Fixed some performance bugs which greatly reduced out-of-memory errors seen in production.
  • July 2020:
    • We upgraded the visual diffing infrastructure and started initial test runs comparing Parsoid rendering and core rendering on a 25K sample of pages from a small set of wikis. We plan to run these tests every week and monitor progress as we fix rendering and functionality gaps. Results are accessible at https://parsoid-vs-core.wmflabs.org/.
    • We prepared Parsoid for MediaWiki 1.35 LTS release so that Parsoid and VisualEditor can be used out of the box.
    • Reduced impedance mismatches between Parsoid and core parser wrt use of concepts around HTML4 block / inline tag notions.
    • Work in Progress:
      • integrating parser test infrastructure between Parsoid and core.
      • Enabling extension tests to be run against Parsoid.
  • April - June 2020:
    • We started addressing functionality gaps in Parsoid (specially error handling in Cite extension) and rendering differences (output for media wikitext).
    • We fine-tuned the Parsoid Extension API further in preparation for wider consultation in the coming months.
    • We implemented a registration mechanism for extensions to hook with Parsoid.
  • Jan - March 2020:
    • We addressed a bunch of technical debt incurred during the porting and integrated Parsoid closer with MediaWiki core.
    • Starting March 2020, Parsoid is deployed as part of the weekly MediaWiki train.
    • We also started drafting a Parsoid Extension API for extensions to hook directly into Parsoid.
  • 2019:
    • Around the end of January, we started porting Parsoid to PHP and by end of the year, successfully completed the project by deploying Parsoid/PHP to the Wikimedia cluster and serving all traffic from it.
    • This blog post provides a good overview of the porting project.
  • 2018:
    • Early experimentation, prototyping and preparation to port Parsoid from JavaScript to PHP. This was low-key background work.
  • 2015 - 2018:
    • HTML4 Tidy was replaced with HTML5 RemexHtml, and while upgrading the MediaWiki infrastructure, it also eliminated one of the biggest sources of rendering differences between Parsoid & the core parser. This blog post is a good overview of the reasons for this replacement and the process of doing this.
  • 2014-2015: See Parsoid/Roadmap/2014 15.
  • 2013-2014: See Parsoid/Roadmap/2013.
  • 2013: 2013 mailing list post by Gabriel Wicke.