I read X’s open-sourced ranking code and the best studies on post performance. Most “viral tweet” advice has no evidence behind it. (I will not promote)

I wanted to know what actually makes a post perform, so I skipped the threads and went to primary sources: X’s published ranking code, a large Buffer dataset (18M+ posts), and a few academic papers on what spreads. What held up: * **Replies matter far more than likes.** In the published weights, a reply is worth roughly 10x a like. Posts that invite a specific, answerable reply beat “thoughts?” endings. * **Concrete beats clever.** In a controlled study of same-author, same-link tweets with different wording, the winners were informative and specific, and they used numbers and names. * **Account context swings reach more than wording does.** Premium status alone was associated with about 10x the reach in Buffer’s data. What didn’t hold up: * Most “analyzed 10,000 viral tweets” posts. They only look at winners, so it’s survivorship bias. * Any tool that promises “X% chance to go viral.” In the best test I found, a model trained on engagement data picked the better of two versions about 74% of the time, and GPT-4o managed about 59%. Coin-flip is 50%. * Hard rules about links and hashtags. The evidence is contested, and even X’s own people have contradicted each other. So the honest ceiling for any “score” is “this draft shares traits with better-performing posts,” not a viral prediction.