Grammarly vs ProWritingAid vs Hemingway: I Ran My 30 Best Posts Through All Three. The Winner Wasn’t Close
Quick context. I have been writing professionally for 12 years, and I have written about 800 published articles across 4 different sites. I am not a beginner. I know what good writing looks like, and I know what my own writing looks like before and after editing. When Grammarly, ProWritingAid, and Hemingway all launched their AI powered editing suites in 2025 and 2026, I wanted to know which one was actually the best, not which one had the best marketing. I ran my 30 best performing posts through all three. The winner was not close, and the loser surprised me. Here is the honest comparison, with the specific scores, the specific changes each tool suggested, and the cases where each tool got it badly wrong.
I am going to walk you through the test setup, the 6 categories I scored on, the per tool performance, the specific use cases each tool is best for, and the pricing comparison. By the end, you will know which one to use, which one to skip, and which one to use only for a specific purpose. The answer is not the one most people would expect, based on name recognition.
How I tested them
I selected my 30 best performing published posts from the last 3 years. The selection criteria. Posts that had over 1,000 page views, that I was proud of as writing, and that represented the range of my work (long form articles, listicles, how tos, opinion pieces, case studies). The posts ranged from 800 words to 3,200 words, and the topics ranged from marketing to freelancing to AI tools.
For each post, I ran it through each tool with the default settings, and I also ran it with the most aggressive “improve clarity” or “rewrite for clarity” setting that the tool offered. The default test was to see what the tool flags without asking for changes. The aggressive test was to see what the tool produces when asked to make it better. Both tests are useful for different reasons. The default test is what the tool catches unprompted. The aggressive test is what the tool thinks “better” looks like.
The 6 categories I scored on
Grammar and spelling. The baseline. Does the tool catch obvious errors like subject verb agreement, wrong word choice, and missing punctuation? Every modern editing tool should be near perfect here, and the differences in this category are small.
Style suggestions. Does the tool flag passive voice, weak verbs, adverbs, and other style issues? The Hemingway app is famous for this category, but I wanted to see how all three compared. The differences here are meaningful, because style suggestions are subjective, and a tool that flags too much becomes noise.
Clarity rewrites. When asked to rewrite a sentence for clarity, how often does the rewrite actually improve the sentence? This is the most important category for me, because the goal of editing is to make the writing clearer, not just to flag issues.
Tone analysis. Does the tool give useful feedback on the overall tone (formal vs casual, confident vs hedging, friendly vs distant)? Tone feedback is hard to do well, because tone is contextual. A casual tone is appropriate for some posts and inappropriate for others. A good tool should give nuanced feedback, not just flag every instance of casual language as a problem.
Plagiarism detection. Important for anyone publishing original work. The tool should catch actual plagiarism, not just flag common phrases. The difference between a good plagiarism checker and a bad one is the false positive rate. A good tool flags actual copying. A bad tool flags every well known phrase as plagiarism.
