What Grammarly is
Grammarly launched in 2009 as a grammar checker and became best known for its browser extension, which underlines mistakes in email, documents and web forms. Today it works across browsers, desktop apps and phone keyboards, and it mixes traditional writing checks with generative AI that can rewrite, summarize and draft.
In 2025 Grammarly's parent company bought the Superhuman email app and, in October 2025, renamed itself Superhuman. The writing assistant keeps the Grammarly name and is now one part of a suite that also includes Superhuman Mail, Superhuman Docs and an assistant called Superhuman Go.
Key features
Spelling, grammar and punctuation
The core checks catch spelling errors, missing words, agreement problems, comma mistakes and confusing sentences. They are on the free plan and work wherever Grammarly is installed.
Clarity, tone and rewrites (Pro)
Pro adds full-sentence rewrites for clarity and concision, tone adjustment (for example, more confident or more friendly), fluency suggestions for non-native speakers, inclusive language and consistency checks such as citation formatting.
Generative AI
Grammarly's AI can draft emails, rewrite paragraphs, summarize text and answer prompts in context. The free plan includes 100 AI prompts a month and Pro includes 2,000; Enterprise is unlimited.
Plagiarism and AI-text detection
Pro checks text against web pages and academic sources for unintended plagiarism and estimates whether text was written by AI. Authorship records how a document was written, which students can share to show their own work.
Writing agents
Since 2025, Grammarly has added specialized AI agents, for example to predict a reader's reactions, suggest citations, or grade an assignment against a rubric. Availability varies by plan.
Pricing (as of October 2026)
From Grammarly's plans page, checked October 2026. The page shows one monthly figure for Pro; pricing trackers report it as the billed-yearly rate.
| Plan | Price | AI prompts | What you get |
|---|---|---|---|
| Free | $0 | 100/month | Spelling, grammar and punctuation, tone detection. |
| Pro | $12/month (reported as billed yearly, $144/year; about $30 month to month) | 2,000/member/month | Rewrites, tone changes, fluency, plagiarism and AI-text detection. Free trial available. |
| Enterprise | Contact sales | Unlimited | SSO, SCIM, custom roles, data loss prevention, bring-your-own-key encryption, audit logs, analytics. Sold through Superhuman Go. |
Grammarly is also included in every plan of the wider Superhuman suite, which lists Pro at $15 per member a month ($12 billed yearly) and Business at $40 ($33 billed yearly), the latter adding Superhuman Mail. Discounts for students and frequent promotions are common.
Strengths
- Works everywhere. Browser extension, desktop apps, Word and Google Docs, and phone keyboards mean one checker across all your writing.
- Good free plan. The free checks catch most everyday mistakes without paying.
- Suggestions, not rewrites by default. You see each change and accept or reject it, which keeps your voice.
- Helpful for non-native speakers. Fluency suggestions are a common reason users give for paying.
- Plagiarism checking. Useful for students and anyone publishing.
Weaknesses
- Overlap with AI chatbots. General assistants now rewrite text well, which makes Pro harder to justify for people who already pay for one.
- Over-correction. A frequent complaint is suggestions that flatten style or misunderstand technical, creative or informal writing.
- Mainly English. Core grammar checks are built for English, though the wider suite advertises writing help in more languages.
- Upselling. Free users see many Pro suggestions they cannot apply, which users often find distracting.
- Pricing clarity. Monthly, yearly and promotional prices differ a lot, and the Superhuman suite adds another layer of plans.
- AI detection is imperfect. No AI detector is reliable enough to prove who wrote a text.
Privacy and security
What Grammarly states, as of October 2026:
- Grammarly says it does not sell user data.
- Text is processed on Grammarly's servers to produce suggestions, so it is not an offline tool.
- Enterprise adds SAML SSO, SCIM, data loss prevention, bring-your-own-key encryption and an audit log API.
- Grammarly publishes security certifications and compliance details in its trust center; check it for the current list if your organization requires specific ones.
- You can turn Grammarly off for specific apps or websites, which is wise for password managers, banking or confidential systems.
Platforms
- Browser extension: Chrome, Edge, Firefox and Safari
- Desktop apps: Windows and macOS (work in most apps)
- Add-ins: Microsoft Word and Outlook, Google Docs
- Mobile: Grammarly keyboard for iPhone and Android
- Web editor at grammarly.com
Alternatives
- QuillBot: stronger for paraphrasing and summarizing, with a grammar checker. See Grammarly vs QuillBot.
- Microsoft Copilot: built into Word and Outlook if you already pay for Microsoft 365.
- Claude and ChatGPT: general assistants that rewrite and edit well when you paste text in.
- Superhuman: if you want Grammarly bundled with a fast email client.
Free vs Pro: what you actually gain
The free plan handles the mistakes that embarrass you: typos, wrong words, missing punctuation and basic grammar. For many people writing emails and short documents, that is all they need, and it costs nothing.
Pro is about how the writing reads rather than whether it is correct. Its suggestions rewrite whole sentences to be shorter or clearer, adjust tone, flag repeated words and passive phrasing, and point out where a non-native phrasing sounds unusual. The plagiarism and AI-text checks matter mostly to students, teachers, publishers and anyone who must show work is original. The jump from 100 to 2,000 AI prompts a month matters only if you use Grammarly's generative AI rather than a separate chatbot.
A practical way to decide: use the free plan for two weeks and watch how many Pro suggestions you would have accepted. If it is a handful, stay free. If it is dozens a day, Pro is likely worth the yearly price.
Tips for using Grammarly well
- Set your goals (audience, formality, intent) on a document so suggestions fit what you are writing.
- Add names, product terms and jargon to your personal dictionary so they stop being flagged.
- Turn Grammarly off on sites where you type sensitive information.
- Treat tone and rewrite suggestions as options, not corrections; keep your own voice where it matters.
Who should use Grammarly
Install Grammarly Free if you write in English and want mistakes caught wherever you type. Upgrade to Pro if you write a lot for work or study, want help with tone and clarity, or need plagiarism checks. If you already pay for an AI assistant and do not mind copying text into it, Pro may not add enough to justify the cost.