I Built a Free Hemingway Editor Alternative That Runs in Your Browser

Readability scoring has a problem. Most writing tools check your text against a single formula — usually Flesch-Kincaid — and give you one number. That number is a guess. Different formulas measure different things (syllable count, word familiarity, sentence length), and they routinely disagree on the same text by 2–4 grade levels. I wanted a tool that used multiple formulas, ran in the browser without uploading text to a server, and gave me more than one metric. I couldn't find one, so I built it. Full disclosure: I'm the creator of ProseScore and the textlens npm package that powers it. The single-formula problem Hemingway Editor is the most popular readability tool for writers. It highlights complex sentences and gives you a grade level. Under the hood, it uses one readability formula. Here's why one formula isn't enough. Consider this sentence: "The oncologist discussed the prognosis with the patient." Flesch-Kincaid gives it a low grade level because the sentence is short (8 words