Grammarly Review 2025: The AI Writing Assistant That Polishes Every Word

The Email That Nearly Cost a Deal

Last spring I sent a proposal to a prospective client worth about forty thousand dollars in annual revenue. In my haste I wrote "your" when I meant "you're" in the opening paragraph and used "affect" where "effect" belonged two sentences later. The client's procurement lead forwarded it back to me with a one-line note: "If attention to detail isn't your strength, we'd prefer to look elsewhere."

That stung. It also made me take Grammarly seriously for the first time. I had always dismissed it as training wheels for people who never learned grammar in school. Turns out, the thing is, even people who know grammar make mistakes under deadline pressure. And those mistakes cost real money.

I have been running Grammarly across my entire workflow for about eight months now. Emails, proposals, Slack messages, LinkedIn posts, internal docs. Here is what matters: does it actually catch meaningful errors, is it worth the subscription, and how does it compare to just asking ChatGPT to proofread your stuff?

What Grammarly Actually Does

Grammarly is a writing assistant. It sits inside your browser, your desktop apps, your phone keyboard, and it watches as you type. When it spots an error -- grammar, spelling, punctuation, awkward phrasing -- it underlines the problem and offers a fix. Red underlines for hard errors. Blue for clarity. Purple for word choice. Green for tone.

That is the free version. The paid version (Premium) adds full-sentence rewrites, vocabulary suggestions, plagiarism detection, and the newer GrammarlyGO generative AI feature, which can draft text, rewrite paragraphs, and summarize documents. The Business tier stacks on style guides, brand voice enforcement, and team analytics.

It works in Chrome, Firefox, Safari, Edge, on Windows and Mac desktop apps, in Microsoft Office plugins, in Google Docs, and even on your phone's keyboard. In my experience, it shows up everywhere I type. The only places I have found it absent are some proprietary enterprise web apps and Google Docs on mobile.

Grammar and Error Detection: The Core Product

This is the bread and butter and it is genuinely good.

I ran a test. Took a 2,000-word draft and introduced 50 deliberate errors -- subject-verb disagreements, comma splices, dangling modifiers, "its" vs. "it's" confusion, misused homophones, run-on sentences. Grammarly caught 47 of them. Word's built-in checker caught 31. Google Docs caught 38.

The three Grammarly missed were edge cases where I made intentional stylistic choices that could technically be flagged either way. So in practice, 47 out of 50 on unambiguous errors. That is a strong showing.

Here is what makes it better than a basic spell checker:

• Context-aware corrections. It correctly distinguishes "its" from "it's" every single time in my testing. Word still gets this wrong occasionally.
• Proper noun recognition. It does not flag company names and technical terms as misspellings once it has seen them a couple of times.
• Compound sentence handling. It catches comma splices without generating false positives on legitimate compound sentences. This is harder than it sounds.
• Explanations with every fix. This is underrated. It does not just tell you to change something. It tells you why. Over time, I found myself making fewer of the errors it used to flag.

The performance score -- rating your writing on correctness, clarity, engagement, and delivery on a 0-100 scale -- is useful as a quick sanity check. I do not obsess over it, but if a document scores below 70, I know I need another pass.

Tone Detection: More Useful Than I Expected

I was skeptical about this one. But tone detection has saved me from sending at least three emails that would have landed badly.

The feature reads your text and tags the perceived tone -- "confident," "friendly," "dismissive," "formal," "concerned," and so on. I wrote a response to a client complaint that Grammarly tagged as "dismissive" and "cold." I reread it. Grammarly was right. The words were fine. The vibe was terrible. I rewrote it in about two minutes and the tone shifted to "empathetic" and "helpful." Problem avoided.

This works best for business writing. Emails, Slack messages, customer-facing copy. It is less useful for creative writing where you might want an edgy or unusual tone on purpose. But for the daily back-and-forth of professional communication, it is like having a colleague glance at your draft before you hit send.

GrammarlyGO: The Generative AI Play

Here is where things get complicated.

GrammarlyGO lets you generate text from prompts, rewrite paragraphs in different tones, summarize documents, and expand notes into full drafts. It works directly inside whatever app Grammarly is installed in, so you do not have to copy-paste to ChatGPT.

I used it to draft five email responses. The results were fine. Not great. Fine. They read like competent first drafts that needed two to three minutes of editing, compared to the ten or fifteen minutes I would have spent writing from scratch. The rewrite feature is better. I pasted in a technical explanation and asked it to simplify for a non-technical audience. The output was clear and needed only minor tweaks.

But here is the thing. GrammarlyGO is not ChatGPT. It is not Claude. It does not handle long, complex, creative writing tasks well. It cannot sustain a narrative voice. It is good for short-form, purpose-driven stuff -- email replies, quick rewrites, summaries. That is its lane and it stays in it.

The free tier gives you 100 GrammarlyGO prompts per month. Premium bumps that to 1,000. For how I use it, 1,000 is plenty.

Plagiarism Checker

Premium only. It scans your text against billions of web pages and academic papers.

I tested it by dropping in three directly copied paragraphs from published articles and two paraphrased passages. It caught all three direct copies and one of the two paraphrases. It is not Turnitin -- it does not have access to the same database of student submissions -- but it is fast and good enough for bloggers, content marketers, and anyone who wants a quick originality check before publishing. A 3,000-word article scanned in under fifteen seconds.

Style Guides and Brand Tones (Business Plan)

If you manage a content team, this is where the Business plan earns its keep.

You define rules: say "customers" not "clients," use "email" not "e-mail," sentence case for headings, avoid jargon in customer-facing copy. Grammarly enforces those rules for everyone on the team. I set up a style guide for a five-person content team and within the first week Grammarly flagged 23 violations that would have slipped through manual editing. Things like inconsistent capitalization, banned phrases, and off-brand tone.

This is a real time-saver for any organization where multiple people write customer-facing content. Consistency is hard. This makes it easier.

Where It Lives: Cross-Platform Presence

The single biggest advantage Grammarly has over ChatGPT and Claude is this: it is already there when you are writing.

No copying. No pasting. No switching tabs. No prompting. It just underlines the problem while you are typing in Gmail, Slack, Notion, LinkedIn, WordPress, or wherever else. That friction difference matters more than you might think. I write maybe sixty to eighty messages a day across different platforms. There is no way I am copying each one into ChatGPT for review. But Grammarly is already watching. The corrections happen in real time.

This is its moat. The technology is not necessarily better than what GPT-4 can do with grammar. But the delivery mechanism -- always-on, always-inline, zero context switching -- makes it far more practical for everyday use.

The Writing Stats: Nice to Have

Grammarly sends a weekly email showing your word count, accuracy rate, unique vocabulary, and tone trends. The in-editor score rates documents on a 0-100 scale.

I tracked my team's scores over three weeks. Average first-draft quality went from 72 to 84. The biggest improvement was clarity -- fewer wordy sentences, less passive voice. Some team members told me they started catching their own mistakes before Grammarly flagged them. That is the real value: it teaches you to write better, not just corrects you after the fact.

What Bugs Me

Is Each Tier Worth It?

Free -- Worth it for: students, casual writers

You get basic grammar, spelling, and punctuation checking. Tone detection. 100 GrammarlyGO prompts per month. It is genuinely useful. If all you need is a spell checker that actually understands context, the free plan delivers.

Premium ($12/month annual, $30/month monthly) -- Worth it for: professionals, freelancers, anyone writing daily

Full-sentence rewrites, vocabulary suggestions, plagiarism detection, 1,000 GrammarlyGO prompts. The clarity suggestions alone make this worthwhile if you write more than a few hundred words a day. The awkward pricing question: ChatGPT Plus costs $20/month and can do everything GrammarlyGO does plus a hundred other things. But it cannot sit inside your Gmail compose window and correct your tone in real time. Different tools, different jobs.

Business ($15/user/month annual) -- Worth it for: content teams of 5+

Style guides, brand tones, admin dashboard, analytics, SAML SSO, 2,000 GrammarlyGO prompts per user. The style guide feature is the differentiator. If you have five or more people writing customer-facing content, the consistency gains pay for themselves. For a team of ten, that is $150/month. Reasonable.

Enterprise (custom pricing) -- Worth it for: large orgs with compliance needs

Custom AI features, advanced security, dedicated support. Call their sales team. If you need this tier, you probably already know it.

Education (custom pricing) -- Worth it for: schools that can get it

Institutional licenses with plagiarism detection and admin analytics. Pricing varies. Worth inquiring about if you run an academic department.

Grammarly vs. the Competition

Against ProWritingAid

ProWritingAid digs deeper into style analysis. Twenty-plus writing reports on pacing, sentence variation, cliches, readability. If you write novels or long-form academic papers and want craft-level feedback, ProWritingAid is worth looking at. Its lifetime license at $399 is attractive for long-term cost savings. But the interface is less polished, real-time suggestions are slower, and it does not live everywhere the way Grammarly does. For daily professional writing, Grammarly wins. For serious long-form craft, give ProWritingAid a trial.

Against ChatGPT and Claude

The existential question for Grammarly. Why pay for a specialized tool when ChatGPT or Claude can check grammar, rewrite, adjust tone, and generate content?

The answer is friction. ChatGPT requires copy, paste, prompt, wait, copy result, paste back. Multiply that by sixty messages a day. Nobody does that. Grammarly runs inline, in real time, with zero thought required. Its grammar accuracy also exceeds what general-purpose models achieve in my testing, and the tone detection plus style guides have no equivalent in ChatGPT or Claude.

For content generation and complex tasks, the general-purpose AIs are better. For real-time writing polish woven into your existing workflow, Grammarly is the better tool. They solve different problems.

Against Hemingway Editor

Hemingway is a scalpel. It does one thing: makes your writing more readable. Color-codes sentences by complexity, flags passive voice, counts adverbs. It does not check grammar, does not detect tone, has no AI features, and runs only as a web app or $19.99 desktop app. I use both. Grammarly for everyday work, Hemingway for a focused editing pass on important pieces. If you are on a tight budget and mainly need readability feedback, Hemingway at twenty bucks one-time is hard to beat.

Who Actually Needs This

• Business professionals writing 20+ emails a day -- the safety net is worth the price
• Students -- grammar correction plus plagiarism detection plus learning from explanations
• Content teams -- style guides keep everyone consistent without manual editing passes
• Non-native English speakers -- catches idiomatic issues that spell check misses
• Customer support teams -- tone detection prevents bad interactions before they happen

Skip it if you are a creative writer who breaks grammar rules on purpose (the constant suggestions will drive you nuts), a technical writer with lots of domain-specific jargon (too many false positives), or someone who already pays for ChatGPT and is comfortable with copy-paste workflows.

The Verdict