The Once-in-a-Lifetime Proofreading Tool
ProWritingAid is an alternative to Grammarly, only more expensive. Valley?
If you're going to write your term paper (or even a dissertation), in some way, it's something you'll do "once in a lifetime." And that's pretty incompatible with subscribing to a review app that covers you every month.
If this is your case, I think it's worth using the trial of ProWritingAid , even if it is an application without support for Portuguese. It's just that ProWritingAid has some very interesting proofreading reports that work regardless of language, especially the one that finds repeated sentences and the one that measures the fulfillment of sentences .
This alone puts your text on another level, as it prevents the repetition of periods and words in several passages, in addition to alerting you to paragraphs that have become incomprehensible due to their length. The tool's website describes these features as follows:

But see that my advice is to use the trial , since the purchase has a very eloquent opposing argument: the price. If you only subscribe for one month, you'll spend at least $20. And that doesn't include the search for plagiarism, which in any case would be of almost no use, since the tool only checks for plagiarism in English.

So the recommendation I make is that you use it only once in your life, because the writing of your monograph is a very important moment not to have a review. If you want to make frequent use of a similar and free tool, the Hemingway It is the most suitable option, as long as it is for quick checks. I reinforce that ProWritingAid has the differential of offering more robust reports than the competition and that, in my view, it has a unique approach to the problem it seeks to solve.
Does this apply to those who write in English? No. After all, for those who write in English, there are cheaper alternatives with good skills, such as Ginger or PerfectIt or Linguix or Trinka and the Grammarly , which is the market leader:

And what are the free options for Portuguese? There will always be Word, which doesn't charge you anything more for a spelling and basic grammar review. In the same way, there is Chrome, if you type in the browser. In addition, Microsoft is investing in the Publisher , a real threat to all the programs I mentioned, mainly because it comes included in the Microsoft 365 package with the same features as the paid alternatives.
Thus, Microsoft Editor's mission seems to be to kill Grammarly, keeping the Office empire free of threats. And only Microsoft can organize itself to the point of offering a robust product to the Brazilian market, considering the current price of the dollar, its tradition and ubiquity.
Meanwhile, the LanguageTool It runs on the outside, offering a solution that theoretically works in Portuguese, but that seems a bit limited to me. The operation of the extension itself and the review board is very good, but the suggestions don't add much to me.
In summary, For those who write in English, the flagship of paid tools is a revision that goes beyond spelling and grammar , including clarity and style suggestions. The selling point of all of them seems to be one and quite terrorist: "don't send an inappropriate email to your boss, because it would cost you even more".
For those who write in Portuguese, the threat is even greater: there is still no great option. For now, the way out for Microsoft users is to continue using Word and Editor. And for those who write in the browser, you can use Chrome's corrector or LanguageTool, despite its limitations.
To conclude: Use what you have. I mean, this applies to everyday life, adding Hemingway's reports or ProWritingAid's trial to proofread those long, once-in-a-lifetime texts.