Growing on X
How the X (Twitter) algorithm works, from its own open-source code
What X’s open-source code says about the For You feed: where posts come from, the weights for likes, replies and reports, and what it means for your replies.
Short answer: X builds the For You feed with a model called Phoenix. For every post it could show you, Phoenix predicts how likely you are to like it, reply, repost, share it, follow the author, or block, mute and report. X multiplies each of those chances by a weight and adds them up. Since August 13, 2026 the weights are public on GitHub: a predicted reply weighs 5, a like 0.66, a report -234. For replies, the code holds two surprises: For You shows a reply mostly to people who already follow its author, and a block or a mute costs far more than a like earns.
Where this comes from
X publishes the code behind its For You feed on GitHub, in a repository called x-algorithm. It came out in three steps:
| Date | What X released |
|---|---|
| January 20, 2026 | The pipeline and the ranking model, without the weights |
| May 15, 2026 | A version you can run, with a small copy of the model |
| August 13, 2026 | The weights, the filters that hide posts, and the labels X puts on posts and accounts |
Since August the code gets updated almost every day. The file with the weights says it mirrors the live defaults, and its last sync before we wrote this was October 14, 2026. Everything below comes from that version, read on October 15. X keeps a few things back, such as some of its spam rules, “to reduce the risk of gaming”, as its README puts it.
How a post gets into your For You feed
- GatherFrom accounts you follow, and accounts you don’t
- FilterToo old, seen, muted, or a stranger’s reply
- ScoreAbout 25 guesses, weighted and added up
- AdjustFewer posts from one author, a lift for new ones
- CheckShow it, warn, or drop it
- Gathering. Posts come from two places at once: accounts you follow, and accounts you don’t. For the second, X looks for posts close to what you engage with, posts popular in the clusters of interest you belong to, and a shared list of popular recent posts.
- First filters. X drops posts older than 48 hours, your own posts, posts you’ve seen, muted words, and accounts you blocked or muted. It also drops replies and reposts from accounts you don’t follow.
- Scoring. Phoenix predicts the chance of about 25 actions for each post, and X adds them up with their weights.
- Adjusting. A second post from the same author counts for less (times 0.625, and never below 0.25). Posts from accounts you don’t follow count times 0.75. A new small account can get one original post lifted into your feed, and a last pass spreads out posts that look alike.
- Visibility check. A separate system decides whether each post may show at all: it can let it through, add a notice, put it behind a warning, or drop it.
The weights
These are the numbers in the code on October 15, 2026. Each one multiplies the predicted chance that you’ll do that thing with the post.
| What the model predicts you’ll do | Weight |
|---|---|
| Share it with a copied link | 20 |
| Reply to it | 5, or 20 on an original post from someone you both follow |
| Quote it | 5 |
| Send it in a DM | 5 |
| Follow the author | 4 |
| Share it | 2 |
| Repost it | 1 |
| Like it | 0.66 |
| Open the author’s profile | 0 |
| Block the author | -31.2 |
| Say you’re not interested | -52.272 |
| Mute the author | -58.8 |
| Report it | -234 |
Source: home-mixer/params/param.rs, synced October 14, 2026.
A big negative number doesn’t mean one report wipes out hundreds of likes. The weights multiply chances, and reports are rare. X wrote this into the code itself:
the baseline probability of a Report is more than 1000x lower than a Like
The numbers also move. The weight for a like was 0.5 in August, 0.6 on October 13 and 0.66 a day later. Read the table as a snapshot.
What the code means for your replies
For You shows your reply to your followers
The first filters drop replies from accounts the reader doesn’t follow. So when you reply to a big account, your reply doesn’t travel through For You to strangers. Strangers find it in one place: the replies under that post. Even for your own followers, a reply counts times 0.75, the same as a post from someone they don’t follow.
Under the post, a different ranking decides
How replies line up under a post isn’t in this code. X’s Help Center describes it instead:
when ranking a reply higher, we consider factors such as if the original post author has replied, if a reply is from someone you follow, or if the person is an X Premium subscriber
A reply the author answers moves up. That’s the strongest case for replying with something the author wants to answer.
Conversations with people you both follow count four times as much
Since July 2026, the chance that you’ll reply to an original post from someone you both follow weighs 20 in place of 5. Nikita Bier, X’s head of product at the time, said the change fixed missing data that had:
made your friends appear less in your replies
In practice, the people you trade replies with see more of your posts, and you see more of theirs.
Blocks and mutes outweigh likes
A predicted mute weighs -58.8 and a like 0.66. X also labels whole accounts from how people respond to them: the README describes a system that labels an account from “blocks, reports and spam reports relative to favorites”. A reply that annoys people costs you more than a liked reply earns. We learned that one the hard way, in We lost a Twitter (X) account because of replies.
The boost for new accounts skips replies
X lifts one original post at a time from small accounts (50,000 followers or fewer) that are less than two hours old and have fewer than 200 views. Replies don’t qualify. To get that lift, post too.
What the code doesn’t tell you
- How replies are ordered under a post. Only the Help Center’s description above.
- Some spam rules and the prompts X gives Grok to judge posts. X keeps those back on purpose.
- Which numbers run for your account right now. The code holds the defaults, and X runs experiments on top of them.
The one thing you can check for yourself is whether X put a label on your posts or your account. X’s Under the Hood report shows it, and we walk through it in X shadowban: how to check with Under the Hood.
Questions
Is the X algorithm open source?
Yes, the For You feed is. The code, the model and, since August 13, 2026, the weights are on GitHub. Some spam rules and the way replies are ordered under a post aren’t.
What does the X algorithm reward most?
Posts people share with a copied link, reply to, quote or send in a DM, and posts from accounts people end up following. Likes count, at a low weight. Blocks, mutes, reports and “not interested” count against a post, heavily.
Do replies help you grow on X?
Replies put your name in front of everyone reading that post, and a reply the author answers rises to the top. For You mostly keeps your replies for your own followers, so new people find you in the threads. Our guide to growing on X builds on that.
Do likes still matter on X?
A little. A predicted like weighs 0.66, against 5 for a reply. A post that gets likes and nothing else won’t travel far.
How often does the X algorithm change?
All the time. The code on GitHub changes almost every day, and the weight for a like changed twice in one week of October 2026.