XThe X Algorithm
A new drop on the 25th of every month

The drops

Each edition draws on four sources: X's public feed code, its policies and Original Content Rewards Program terms, its Under the Hood reports, and measurements collected by our own software through the X API.

The code explains how the system is designed to work. Our software tracks results from posts on live accounts, including impressions, replies, and follows. We review all four sources before each release and update the book to reflect our findings.

Timeline: what X changed, when we dropped

X has no schedule; its code and rules change when they change. The book drops on the 25th of every month, after X's monthly report.

Oct 25, 2026We droppedThe Edition III drop
Oct 7, 2026X pushedX's code turns on a popular-posts source for the For You feed
Sep 30, 2026X pushedX's code widens the new-author boost from accounts under 1,000 followers to accounts under 50,000
Sep 29, 2026X pushedX's code changes several ranking weights: not interested, click, and dwell after a click
Sep 24, 2026We droppedThe Edition II drop
Sep 21, 2026We droppedThe Edition I drop
Sep 18, 2026X pushedUnder the Hood reports add legal takedowns by country
Aug 14, 2026X pushedX adds notes on how the weights work and the Brazil 2026 election filter
Aug 13, 2026X pushedX publishes the rest of the feed code: the weights, the filters, the enforcement rules, the Phoenix training code
May 2026X pushedX updates the public repository
January 2026X pushedX releases the new For You code: one trained model, Phoenix, replaces the hand-built ranking pipeline
Mar 31, 2023X pushedTwitter publishes its recommendation algorithm for the first time (the-algorithm repository)
Edition III
Oct 25, 2026 · 158 pages
  • The new-author lift changed in X's code on September 30. It now covers accounts up to 50,000 followers, not 1,000. It applies to a post's first two hours and first 200 impressions, not 48 hours and 1,000. X now picks among eligible posts by likes against views. The chapter says exactly how.
  • Weights changed in X's code on September 29. Click is 0.3. Not interested is -47.52, which is 95.04 times a like. Time on the post after opening it is 0.4, up from zero.
  • Five weights now differ between the two copies in X's code. The book uses the ranking service's values and explains the difference.
  • New: a shared popular-posts list is a fourth source of posts in the feed, on by default since October 7. A new filter keeps each source's share of the pile in proportion.
  • Visibility now has four answers. Notice is the new one. Trusted Friends posts and a Brazil election label are new rules. The rules moved to new files, and the counts are still 30 shared and 24 recommendation-only.
  • New label: BRAZIL_ELECTION_LEGAL.
  • The enforcement rules were re-read from X's settings of October 20. The machine-written account label now lasts seven days, not 30. Rules for fake accounts and clusters were replaced by bot-detection and liveness-check rules.
  • Correction: the 50 in X's public rule file is a placeholder, not the real credibility cutoff. X says so in the file. The book no longer treats it as the cutoff.
  • Chapter 3: X now sells Premium through The X Subscription, with the plans Plus, Premium, Super, and Ultra. The word Premium now names two things, and the chapter explains both.
  • Chapter 19: the list of what does not count as a qualified impression was updated, and the contact for leaving the program is now @Subscriptions.
  • Chapter 17: the September report was produced on October 7. Reports come out early the following month, not on a fixed day.
  • Read against X's code at commit 6258a15.
Edition II
Sep 24, 2026 · 147 pages
  • X said in its own code that reading the action weights as like-for-like counts is wrong. The weights table now says what the weights actually do, and not one of the values changed.
  • Why a report is weighted 468 times a like: a report is more than a thousand times rarer than a like, so its prediction needs a large weight to move the score at all. The number is about rarity, not damage.
  • New: why mass reporting and group-chat brigades do not work on ranking, in X's own words, and why the engagement you organise for yourself the same way counts just as little.
  • Nothing is rounded any more. The mute and not-interested figures read -117.6 and -86.4 rather than -118 and -86.
  • Author diversity: the real formula and its multipliers, 1, 0.625, 0.4375, approaching a floor of 0.25 rather than reaching a quarter on the third post.
  • The mutual-follow boost applies to the reply weight, not to the whole post score, and only when that person already follows you.
  • The similarity reordering was explained backwards. Raising the setting puts more weight on score, not on variety.
  • The new-author lift raises an already-retrieved post to the level of the sixteenth candidate. It is a place in the pile, not a promised place on the screen.
  • Credibility: the 50 check is not a blanket exemption, the Botmaker feature uses 54, replies are not an input to the score, and Premium is a qualified case.
  • Thunder hands over a reply to an original post without the viewer following that author. The follow-both rule belongs to replies to replies.
  • The Under the Hood report is not a clean bill of health: it maps an allowlist, and it needs an account over 365 days old with ten eligible posts.
  • Read the report's label lists, not its totals. A total is written only when the matching list is empty.
  • The 90-day threshold is a rolling window. Dividing 500,000 by a daily figure does not work: at 2,000 a day the total settles at 180,000 and never arrives.
  • API reads are billed per record returned and writes per request, so reading is not automatically the expensive half.
  • 48 hours is a limit on the feed's candidates, not the end of a post everywhere on X.
  • Visibility rule counts corrected to 30 shared and 24 recommendation-only. Two parameters renamed to DppTheta and DppMaxSelectedRank.
  • Appendix C: Basic belongs with the Premium tiers for post length and editing, not with Free.
  • Read against X's code at commit 44d37eb.
Edition I
Sep 21, 2026 · 144 pages
  • The first drop.