The first time I ran the same 2000-word draft through both Grammarly and ProWritingAid, I expected similar results. Grammar checkers that catch comma splices and suggest better words. Standard stuff.
Instead, Grammarly flagged 43 issues. ProWritingAid flagged 127.
That gap made me suspicious. Was ProWritingAid being too aggressive? Was Grammarly missing half the problems? So I spent two weeks testing both across five types of writing: blog posts, client emails, technical documentation, a short story, and a funding proposal. I tracked every suggestion each tool made, counted how many I actually accepted, and noted where each one fell apart.
Here's what I found.
The Pain Point
You stare at a paragraph and something feels off. Not grammatically wrong — Grammarly gives you a green checkmark. It just reads… flat. Repetitive sentence starts. Passive voice you didn't notice. A paragraph that drags because every sentence is the same length. Grammarly doesn't flag any of this. ProWritingAid does.
But on Monday morning when you need to fire off three client emails and a Slack update in twenty minutes, ProWritingAid's 127-suggestion wall of text would make you close your laptop and walk away. Grammarly catches the embarrassing stuff — the "their" instead of "there," the sentence fragment that makes you look sloppy — and gets out of your way.
These tools solve fundamentally different problems, and picking the wrong one will either bury you in noise or leave your writing superficially clean but structurally broken.
Quick Verdict
Pick Grammarly if: You write short-form content daily (emails, Slack, social posts, quick reports). Speed and integration breadth matter more than stylistic depth. You want real-time corrections while typing.
Pick ProWritingAid if: You write long-form content (articles, books, essays, documentation). You want to improve as a writer, not just fix mistakes. You're fine running a report after drafting rather than getting inline suggestions.
Pick both if: You write for a living. Grammarly in-browser for real-time cleanup, ProWritingAid for a final deep pass before publishing.
Grammarly: What It Actually Does Well
I use Grammarly Premium. $12/month on the annual plan. It sits in my browser as an extension and a little green G badge appears in text fields across Gmail, Google Docs, Slack, LinkedIn, Notion — basically everywhere I type.
What it catches
The grammar engine is legitimately good. It caught a dangling modifier I'd read five times without noticing: "After reviewing the quarterly numbers, the strategy was clearly working." (Who reviewed? Not the strategy.) It caught subject-verb disagreement in a sentence with a long prepositional phrase separating them. It flagged "less" where it should have been "fewer."
The tone detector is the feature I didn't know I needed. It rates your writing on a scale from formal to casual, and offers full-sentence rewrites. When I wrote a terse "Need those numbers by Thursday" to a client, it suggested "Could you share those numbers by Thursday? Appreciate it." — same request, half the perceived aggression. For someone who writes bluntly by default, this alone justifies the subscription.
Where it falls short
Grammarly has no concept of structure. It won't tell you that three of your last four sentences started with "The." It won't flag that you used "however" four times in one paragraph. It won't point out that your 45-word sentence followed by a 4-word fragment creates a rhythm problem.
It's also weirdly conservative about style. I wrote "the onboarding flow is a mess" and it suggested "the onboarding flow is disorganized." One of those sentences sounds like a human. The other sounds like a performance review.
The plagiarism checker exists but I've used it twice. It checks against web pages and academic databases. Useful if you have ghostwriters or work with freelancers. Not something I need daily.
Biggest win: Catching tone-deaf emails before I hit send. Saved me from myself at least three times in two weeks.
Fatal flaw: Zero structural awareness. It'll give your grammatically perfect but rhythmically broken prose a green checkmark.
ProWritingAid: The Writer's Power Tool
ProWritingAid is the opposite. Where Grammarly is a sharp pocket knife, ProWritingAid is a full woodworking shop. More tools than you know what to do with, and a learning curve that makes the first week frustrating.
I paid $120 for the annual Premium plan (it was on sale for $60. Their sales are frequent and aggressive, never pay full price). There's also a lifetime option at $399 which, if you write professionally for more than three years, is the obvious choice.
The reports that actually matter
ProWritingAid generates 25+ reports on your writing. Most are noise. Five changed how I edit:
1. Sentence Length Graph: A visual bar chart of your sentences by word count. The first time I ran it on a blog post, the graph looked like a flat line. Every sentence between 18-22 words. Monotonous. No rhythm. I now aim for variation: short sentences under 8 words followed by longer ones that breathe.
2. Repeats Check: Flags words and phrases you use too often within a tight window. I discovered I say "essentially" way too much. Also "just," "actually," and "specifically." Four words I now hunt down in every draft. Grammarly would never catch this because each individual use is grammatically fine.
3. Sticky Sentences: Highlights sentences where glue words (prepositions, conjunctions, articles) make up more than 40% of the total. These sentences feel harder to read even when you can't articulate why. Fixing them usually means splitting one sentence into two or cutting filler.
4. Pacing Check: For fiction or narrative writing, this identifies sections where nothing happens — pages of introspection or description with zero action beats. Not relevant for blog posts but invaluable for my short story experiment.
5. Dialogue Tags: In my short story test, it flagged "she said" appearing 14 times in 800 words and suggested replacing half with action beats. "She said, reaching for her coffee" becomes "She reached for her coffee. 'I'm not sure that's true.'" A small change that made the dialogue feel more alive.
Where it falls short
The interface is clunky. Reports run sequentially, not in real time. You paste your text, click "Run Report," wait a few seconds, then scroll through findings. This is fine for editing a finished draft. It's terrible for writing emails.
The grammar checker is less accurate than Grammarly's. It caught about 85% of the deliberate errors I planted compared to Grammarly's near-perfect score. It flagged two things as errors that were actually correct, including a perfectly valid semicolon use.
ProWritingAid also doesn't integrate with Google Docs natively. There's a Chrome extension but it's inconsistent — sometimes it attaches to your doc, sometimes it doesn't. I ended up writing in Google Docs, copying the final draft into ProWritingAid's web editor for the deep pass, then pasting back. Clunky but functional.
Biggest win: The Repeats report caught 14 instances of "essentially" across a 3000-word draft. I removed 12 of them. The prose tightened up immediately. No grammar checker would flag this.
Fatal flaw: The UX assumes you have time. You don't run ProWritingAid at 8:47 AM before a 9:00 meeting.
Pricing Breakdown
| Plan | Grammarly | ProWritingAid | |---|---|---| | Free | Grammar + spelling + tone detection | 500-word limit, basic grammar | | Monthly | $30/month | $20/month | | Annual | $144/year ($12/month) | $120/year ($10/month, often $60 on sale) | | Lifetime | Not available | $399 one-time | | Business/Teams | $15/user/month (3+ users) | $12/user/month (2+ users) | | Plagiarism | Included in Premium | 10 checks/year on Premium, 60 on Premium Pro |
ProWritingAid's pricing is the clear winner, especially at sale price. But "cheaper" doesn't matter if you never use it because the workflow friction is too high.
Real-World Test Results
I ran five 400-word writing samples through both tools and tracked accepted suggestions:
| Writing Type | Grammarly Suggestions | Accepted | ProWritingAid Suggestions | Accepted | |---|---|---|---|---| | Blog post | 12 | 10 (83%) | 31 | 19 (61%) | | Client email | 8 | 6 (75%) | 22 | 5 (23%) | | Tech docs | 5 | 5 (100%) | 14 | 7 (50%) | | Short story | 9 | 5 (56%) | 41 | 28 (68%) | | Funding proposal | 11 | 9 (82%) | 27 | 14 (52%) |
The pattern is clear. Grammarly's suggestions have a higher acceptance rate because they're conservative — it only suggests changes it's confident about. ProWritingAid throws everything at the wall, forcing you to decide. For short fiction, that depth is useful (68% acceptance, the highest of any category). For client emails, it's noise (23%).
Who Should Use Which
Grammarly is for people who write to communicate, not to craft. If your writing is a tool (emails, reports, internal docs, Slack messages), Grammarly's speed and integration breadth are the right trade-off. The tone detector alone has prevented me from sounding like a jerk to clients on Thursday afternoons when I'm tired and blunt.
ProWritingAid is for people who think about their writing. If you publish blog posts, books, essays, or any long-form content where structure matters, ProWritingAid's reports will catch things that readers feel but can't name. Sentence length monotony. Echo words. Glue-heavy prose. These are invisible problems — your writing isn't wrong, it's just harder to read than it should be.
Use both if you write professionally. Grammarly for the first draft (real-time cleanup while you type), ProWritingAid for the final pass (structural polish before publish). The combination catches both surface errors and deep problems. I've been doing this for six months and my rejection rate on first drafts has dropped noticeably — editors send back fewer structural notes.
What Neither Tool Fixes
No grammar checker will tell you that your argument is weak or your evidence is thin. Neither will flag that your introduction meanders for 200 words before getting to the point. ProWritingAid's pacing report hints at structural issues but can't diagnose whether your logic holds together.
The real work of writing — structuring an argument, picking the right examples, knowing what to cut — still happens in your head. These tools clean up the execution. They don't do the thinking.
And both tools struggle with technical writing. Jargon, code snippets, and field-specific terminology confuse the grammar engines. Grammarly once suggested I change "the API returns a 200 status" to "the API returns 200 statuses." ProWritingAid flagged "the function takes three arguments" as potentially sexist language. You'll spend time dismissing suggestions in technical contexts.
Alternatives Worth Considering
Grammarly and ProWritingAid aren't the only players. Three alternatives I've tested that deserve a mention:
Hemingway Editor ($19.99 one-time, desktop app) doesn't check grammar at all. Instead it highlights hard-to-read sentences, passive voice, and adverb overuse. Hemingway is the editing equivalent of a stopwatch — it tells you where you're slowing readers down but doesn't suggest fixes. I use it as a third pass after ProWritingAid, specifically to hunt sentences above a 9th-grade reading level. Pair it with either Grammarly or ProWritingAid but don't use it alone. Best for: writers who want a brutal readability score, not grammar corrections.
LanguageTool is the open-source alternative to Grammarly. Free tier catches basic grammar and offers a self-hosted option for privacy-conscious teams. Premium is $5/month — cheaper than both Grammarly and ProWritingAid. It supports 30+ languages, which matters if you write in German, French, or Spanish alongside English. The grammar engine isn't as polished as Grammarly's, but for multilingual writers, it's the only serious option. Best for: non-native English speakers writing in multiple languages.
QuillBot ($9.95/month) focuses on paraphrasing — it rewrites sentences with adjustable fluency and tone sliders. Grammarly can rewrite individual sentences but QuillBot gives you seven variants at once and lets you pick. For writers who struggle with repetitive phrasing (everyone, eventually), QuillBot is a faster way out of a sentence rut than staring at the ceiling. Best for: writers who get stuck on individual sentences and need a creativity jumpstart.
I still default to Grammarly + ProWritingAid, but Hemingway gets opened for long-form pieces and LanguageTool is my recommendation when someone asks "what's the cheapest option that actually works?"
Building a writing tool? LaunchToolsAI has a free Submit AI page — no listing fee, just real screenshots and an honest review. If your editor catches things Grammarly misses, I want to test it.
How to Get the Most Out of Either Tool
After two years of daily use and two weeks of side-by-side testing, three habits made the biggest difference:
1. Don't blindly accept suggestions. Both tools are wrong roughly 15-25% of the time depending on context. Grammarly's tone suggestions flatten personality — it wants your writing to sound like a LinkedIn post. ProWritingAid's style reports sometimes optimize for rules over rhythm. Read every suggestion. Accept what makes your writing better, not what makes the tool happy.
2. Run grammar checks last. Write your draft. Walk away. Come back and edit for structure. Then run the grammar checker. If you fix commas while drafting, you interrupt the flow. Grammar is a polishing step, not a composing step. ProWritingAid's report-based model actually encourages this workflow naturally. Grammarly's real-time corrections tempt you to fix as you go — resist.
3. Build a rejection reflex for certain suggestions. Grammarly will always suggest simpler words: "utilize" becomes "use," "demonstrate" becomes "show." Sometimes simpler is better. Sometimes "utilize" is the right word for the context and rhythm. After a month of using either tool, you develop a feel for which categories of suggestions to auto-reject. For me: I reject roughly half of Grammarly's vocabulary suggestions and a third of ProWritingAid's pacing flags. Your mix will be different.
AI and the Future of Writing Assistants
Both Grammarly and ProWritingAid added generative AI features in 2025, and the results are mixed. Grammarly's "strategic suggestions" can now generate paragraphs from prompts, but the output reads like every other AI-written paragraph you've seen — competent, bloodless, indistinguishable from ChatGPT. I tested it on three blog intros and deleted all three.
ProWritingAid's AI features are more restrained. Their "Sparks" tool suggests alternatives for weak sentences rather than rewriting entire paragraphs. The suggestions are shorter, more targeted, and feel like an editor's margin notes rather than a replacement for your voice. I've kept roughly half of the Sparks suggestions in my workflow.
If you want full AI writing (generate a draft from a prompt), neither Grammarly nor ProWritingAid is the right tool. You want a dedicated AI writer like Jasper, ChatGPT, or Claude for that. Check our best AI writing tools roundup for a full breakdown of all 10 options with pricing and real test results. Grammarly and ProWritingAid are editors, not writers. Keep them in that lane and they're excellent at it. Push them toward generation and you get the same mediocre AI prose everyone else is publishing.
The best writing in 2026 still starts with a human sitting down to type something real. The tools clean it up. They don't create it. And that's probably the right division of labor for now.
Bottom Line
If you write for work and can only pick one: Grammarly. The integration breadth (every app you type in) and tone detector make it the tool you'll actually use every day.
If you publish long-form content at least twice a month and care about becoming a better writer: ProWritingAid. The structural reports will change how you think about prose. The sentence length graph alone has made me a better editor.
If you write professionally (author, journalist, content marketer, technical writer): Get both. Grammarly Premium ($144/year) is the safety net while drafting. ProWritingAid Premium ($60/year on sale) is the polish before publish. $204/year combined is less than most writers spend on coffee.
I pay for both. I use Grammarly every day and ProWritingAid twice a week. If I had to cut one, I'd keep Grammarly — not because it's better, but because I'd stop using ProWritingAid's web editor if I didn't have a publishing deadline forcing me to. Convenience wins. But my writing would be worse for it.
Bookmark this comparison — AI writing tools update pricing models roughly every 8 months, and I update this page whenever plans change. If they launch a lifetime Grammarly plan at $199 tomorrow, you'll see the note here before their email campaign lands in your inbox.