Grammarly vs. ProWritingAid — The Battle of the Tools

As a non-native speaker — and maybe for the English everyman — you are never sure whether you are writing your best English or just English laced with the occasional error in spelling or grammar. Sure, most word processors and even the Internet Explorer have built-in checking tools, but still there is a lot you can do wrong. Specialized tools like Grammarly and ProWriteAid promise to improve your writing. This post will concentrate on a side by side comparison of the tools, for those functions that I use them mostly. I am aware that both have different pricing schema and different features that might be useful for one or the other reader.

A few years back, I bought ProWriteAid in a lifetime license deal and used it ever since. In the last year, though, Grammarly bombed me with advertising, especially online. There is no YouTube watching or Facebook timeline where I do not see the nicely done advertisings. I became curious what the difference might be.

Let’s have a look how these tools play against each other. I concentrate on the three core disciplines grammar, spelling, and punctuation. Both tools offer much more checks on style and habits (like pointing out phrase repeats, sticky sentences that are hard to read, overused word) but that would be too much for a single post.

Just as a disclaimer: this is not an “influencer” blogpost, no money flowed (unfortunately) in the making of this post, I have no relationship with either company except for the fact that I use their products for my writings.

Let’s see how both tools, Grammarly and ProWritingAid, are facing off on the final edit of one chapter of my latest book ”. “Final edit” means for me: everything I could have done with my knowledge of the English language has been done and I am ready to send the book off to the editor. I take the chapter text and feed it to the two tools. Let’s see what happens.

Workflow integration

This of course is a very personal judgement, as it depends very much on how you use the tools in your writing process. Both tools offer a generic interface where you are able to copy and paste your text, do the corrections, and then afterwards retrieve it by the same method.

Grammarly has plug ins to Word and common browsers like Chrome, whereas ProWritingAid lets you load full documents into its application. This is where ProWritingAid shines for me, as it lets me upload my whole Scrivener project and applies the corrections directly into the project. No copy and paste for me!

Clear win for ProWritingAid.

Grammarly: 0 — ProWritingAid: 1

The user interface — both do their jobs

Both tools have the same user interface principle. They show the text with potential issues marked up. And then with an overlay (ProWritingAid) or in a separate screen section (Grammarly) an explainer of the issue and the suggestion how to fix it. By clicking on the suggestion the text is corrected immediately. I can also decide to ignore the issue or to add an unknown word into the user directory so that it won’t show up again. Both tools also have sort of an overview list of all the issues detected for easier navigation. Grammarly is a bit more cleaned up in its approach, but it’s not enough to let me say it wins the contest.


Screen Layout ProWritingAid

Screen Layout ProWritingAid

Screen Layout Grammarly

Screen Layout Grammarly

Both interfaces work fine for a user when it comes to spelling and grammar checks. Let’s call it a draw!

Grammarly: 1 — ProWritingAird: 2

Checking Quality — Grammarly beats ProWritingAid into the ground

 This is the juice of course! How do both tools fare on my chapter from Teen Vampire Hunters? The text is picked from the latest workin-progress of my Teen Monster Hunters young adult series about three friends in the duty of the SIA—the Supernatural Investigation Agency. I took a random chapter which I already edited heavily and Word and Scrivener spelling checks have done their jobs many times. Plus my brain in many endless nightly writing sessions. How I HATE editing!

Some stats first: All in all, both tools together spotted 37 issues in my chapter of 2400 words. ProWritingAid marked 21 issues and Grammarly 27.

The first result that amazed me most: each tool detected in majority issues that the other did not. Only 11 issues were an overlap, detected by both tools. Example: the obvious spelling errors like “intructions” and the propose correction “instructions”. But when it came to language suggestions, the tools run on different engines.

Sometimes they are not even one opinion in the classification of an error. Have a look at the “Whatever – What ever” example from above. ProWritingAid declares it as a grammar issue, Grammarly as a spelling issue.

Let us have a closer look: here are first lines of the blow by blow account of the full result of both tool’s scans (G: Grammar, S: Spelling, P: Punctuation, I left out any personal names findings). In each case, I decided whether to keep the text as is or to take over the suggestion of the tool.

Excerpt of ProWritingAid and Grammarly checking results

Excerpt of ProWritingAid and Grammarly checking results

To keep score, let us count the quality of the findings by adding up the “correct actions”. What are correct actions? Simple:

  • Either the tool has found an issue and I followed the suggestion.

  • Or the tool kept still where the other too had made a suggestion and I decided to keep things as they were (Example: “… Sally said, as the vampire ran away.” Grammarly tells me to remove the comma, but ProWritingAids ignorance is the correct action (only in standard phrases like “as long as” you are adding a comma.)

In one case “ax / axe”, I decided to keep the “axe” as “axe to grind” looks better than “ax to grind”. Grammarly’s suggestion was correct, though, from a spelling alternative perspective. I didn’t add this “issue” into the count.
And here is the tally:

Total “Correct Actions” for ProWritingAid and Grammarly

Total “Correct Actions” for ProWritingAid and Grammarly

By a wide margin, Grammarly scores this very important point: the quality of the check itself. But even then, the loser still made 11 suggestions that were NOT captured by Grammarly. Makes you think, too.

Clear winner: Grammarly

Grammarly: 2 — ProWritingAid: 2


Don’t take the score too seriously, please. It’s a draw in my count, but it’s maybe not a fair count. In the main discipline, Grammarly clearly outsmarted ProWritingAid, so this should count higher. In theory. But for me, the cutting and pasting thing is crazy! I hate it, so I like to use PWA for its great integration with Scrivener, my core tool for writing on my Mac and on the iPad.

In real life this quality of the checks brings us to the main dilemma: Do I need to use both tools to become “close to perfect” in my writings? I leave that decision up to you as there are other factors that need to be considered, which I will inspect in one of my next blogposts.

One other point that may not be obvious: when you run these tools, you start editing over and over again. There were two issues found that made me not only take over the suggestion but made me rephrase the whole paragraph. That was also the reason why the obvious spelling errors were not captured earlier, edit turns to re-edit, messing some things up once more.

But hey, this is a writer’s life!