Most writing tools ask you to visit them; Grammarly built its business on going wherever the writing already happens, quietly checking grammar and tone inside Gmail, Google Docs, Slack, and dozens of other apps without requiring a separate destination. That everywhere-at-once approach has made it one of the most widely used writing tools in the world, with over 30 million users relying on it for everyday correction.
What is Grammarly?
Grammarly is an AI-powered writing assistant that checks grammar, spelling, punctuation, clarity, and tone across virtually any app where a person types, functioning as a browser extension, desktop app, mobile keyboard, and native integration with tools like Google Docs and Microsoft Office. Founded in 2009, Grammarly has evolved well past basic proofreading into a broader generative writing assistant capable of full-sentence rewrites, tone adjustment, and plagiarism and AI-text detection. In late 2025, Grammarly's parent company rebranded to Superhuman following its acquisition of the Superhuman email client, though the writing product itself is still called Grammarly and continues to operate as its own distinct tool.
Key features
Real-Time Grammar and Spelling Checks
Grammarly flags grammar, spelling, and punctuation errors as a person types, working across browsers, desktop apps, and mobile keyboards rather than requiring a separate proofreading step.
Full-Sentence Rewrites
Beyond flagging individual errors, Grammarly can rewrite entire sentences for clarity, conciseness, or a specific tone, going further than traditional grammar-checking tools.
Tone Detection and Adjustment
The assistant identifies how a piece of writing is likely to come across, formal, friendly, confident, and suggests adjustments to better match the intended tone.
Plagiarism and AI-Text Detection
Pro-tier users get access to plagiarism checking and AI-generated text detection, useful for students, editors, and anyone needing to verify originality.
Style Guide and Brand Tone
Teams can define a shared style guide and brand tone that Grammarly applies consistently across every team member's writing, supporting brand consistency at scale.
Cross-Platform Availability
Grammarly works consistently across browsers, Windows and macOS desktop apps, iOS and Android keyboards, and native integrations with Google Docs, Microsoft Office, and Slack.
Pros
- Works inside the apps people already use rather than requiring a separate destination
- Free tier is genuinely capable, covering core grammar and spelling checks along with 100 AI prompts per month
- Full-sentence rewrites and tone adjustment go well beyond basic proofreading
- Broad platform coverage across browser, desktop, mobile, and major productivity apps
- Strong reputation for reliability, with a large, long-established user base
Cons
- Monthly billing costs significantly more than annual billing, a 150 percent markup for the same Pro plan
- No standalone Business plan anymore; Premium and Business were folded into a single Pro tier
- AI prompt caps, 100 per month on Free and 2,000 per member on Pro, can feel limiting for heavy generative use
- No prompt top-up option; running out means waiting for the monthly reset or upgrading
Pricing
Grammarly's Free plan costs nothing and includes basic grammar and spelling checks, tone detection, and 100 AI prompts per month. Pro costs $12 per month billed annually, $20 per month billed quarterly, or $30 per month billed month-to-month, and includes full-sentence rewrites, plagiarism and AI-text detection, and 2,000 AI prompts per member, supporting teams of up to 149 members. Enterprise pricing is custom and quote-based for larger organizations needing centralized administration and unlimited AI usage. Because billing frequency affects Grammarly's price so significantly, users should confirm current rates directly on Grammarly's official pricing page before subscribing.
Best for
Grammarly is well suited to anyone who writes daily, students, professionals, non-native English speakers, and teams up to 149 members who want consistent grammar, clarity, and tone support built directly into their existing apps. It's a particularly strong fit for people who want writing help to feel invisible rather than requiring a separate tool to open. Readers can browse our AI Writing category for related tools.
Use cases
- Catching grammar and spelling errors automatically while writing emails or documents
- Adjusting the tone of a message before sending it to make sure it lands as intended
- Checking a document for plagiarism or AI-generated content before submission
- Maintaining a consistent brand voice and style guide across a writing team
- Getting writing feedback directly inside Gmail, Google Docs, or Microsoft Word without switching tools
Supported platforms
- Grammarly is available through a browser extension, native desktop apps for Windows and macOS, mobile keyboards for iOS and Android, and direct integrations with major productivity apps including Google Docs and Microsoft Office.
Languages
- Grammarly's core grammar and writing checks are built for English. The company has not published a comprehensive list of additional supported languages for its generative AI features, so users needing multilingual writing support should confirm current capabilities directly with Grammarly.
Integrations
- Grammarly integrates with a wide range of everyday tools, including Google Docs, Microsoft Office, Gmail, and Slack, letting its suggestions appear directly inside whatever app a person is already writing in. Enterprise customers get access to additional centralized administration and security integrations through Superhuman Go.
Things to consider
- Because Grammarly's monthly billing costs substantially more than annual billing for the same Pro plan, teams and individuals planning to use it long-term should strongly consider annual billing to avoid paying a significant premium. It's also worth understanding that Grammarly doesn't sell prompt top-ups, so teams with heavy generative AI needs should model their expected monthly usage against the 2,000 prompt cap before assuming Pro will be sufficient.
How the tool compares
Grammarly's most direct comparison in general-purpose writing correction is dedicated grammar tools that focus solely on error-checking without generative rewrites, though Grammarly's broader AI features set it apart from those simpler alternatives. For teams also producing marketing content at scale rather than day-to-day writing correction, a platform like Jasper AI addresses a different, more campaign-focused need. Readers can also browse our Best AI Tools for Freelancers guide for related tools.
AIToolister verdict
Grammarly remains one of the most practical AI writing tools available specifically because it doesn't ask users to change their workflow, it shows up inside the apps people already use and quietly improves the writing happening there. Its free tier is genuinely useful on its own, and Pro's full-sentence rewrites and tone adjustment offer real value for anyone who writes as part of their job. The main decision point is billing frequency, since paying monthly rather than annually meaningfully changes the value equation, and anyone budgeting for consistent use should plan around the annual rate.
Frequently asked questions
- Is Grammarly free to use?
Yes. Grammarly's Free plan includes basic grammar, spelling, and tone checks along with 100 AI prompts per month, with no payment details required.
- How much does Grammarly Pro cost?
Pro costs $12 per month billed annually, $20 per month billed quarterly, or $30 per month billed month-to-month, a significant difference depending on billing frequency.
- Does Grammarly still offer a separate Business plan?
No. Grammarly folded its former Premium and Business plans into a single Pro tier that supports both individuals and teams of up to 149 members.
- Can Grammarly detect AI-generated text and plagiarism?
Yes. Pro-tier users get access to plagiarism detection and AI-generated text detection alongside Grammarly's core grammar and writing feedback.
- What apps does Grammarly work with?
Grammarly works across browsers, Windows and macOS desktop apps, iOS and Android mobile keyboards, and direct integrations with apps including Google Docs, Microsoft Office, Gmail, and Slack.