Grammarly AI

Positioning

Grammarly is the default. That is the honest summary of its position in this category: the writing assistant most people have encountered first, with the widest distribution and the deepest integration footprint, and now one product inside a larger company that has been assembled by acquisition. Grammarly was founded in 2009 by Max Lytvyn, Alex Shevchenko and Dmytro Lider and developed largely in Ukraine; the company is now headquartered in San Francisco and, following acquisitions of Coda in 2024 and the email client Superhuman in July 2025, the corporate entity describes itself as part of the "Superhuman Suite." The plans page states more than 40 million people and 50,000 organisations use the product — a vendor claim, but the scale is not seriously in dispute.

What that reach buys you is ubiquity: Grammarly runs as a browser extension, a desktop app, a web editor, and integrations across email, documents and messaging surfaces, checking your writing where you actually write it. The AI layer arrived on top of a grammar engine that had been maturing for over a decade, and the current product mixes the two: corrections and tone feedback for everything, generative prompts and rewrites metered by plan.

What it actually does

At the free tier, Grammarly checks spelling, grammar and punctuation, shows your writing's tone, and gives you 100 AI prompts per month for generation and rewriting. The paid tier — now called Pro, absorbing what used to be Premium and Business — adds full-sentence rewrites, tone adjustment, fluency suggestions for English, inclusive-language and citation consistency checks, plagiarism detection plus AI-generated-text detection, and 2,000 AI prompts per member per month. Team features land at Pro as well: style guides (one at Pro), brand tones (one at Pro), team analytics, user groups. Enterprise adds unlimited prompts, SAML single sign-on, SCIM, data loss prevention, custom roles, BYOK encryption, audit-log APIs, dedicated support and more, priced by sales quote.

Pricing at time of writing, from Grammarly's own support and plans pages: Free at US$0; Pro at US$12 per member per month billed annually (US$144 per year) or US$30 billed monthly (quarterly billing is US$60 per three months); Enterprise on quote. The Pro tier offers a trial — the checkout flow references a trial with an email reminder two days before it ends. The style-guide and brand-tone tools matter more than they sound: in an organisation, enforcing a shared vocabulary and tone is the difference between a personal proofreader and a team system, and Grammarly is one of the few tools in this category where that layer is mature.

My testing notes

Two observations from my own use and testing. First, the grammar engine is still the reason to pay. In my tests on a deliberately corrupted sample — subject-verb disagreements, dangling modifiers, comma splices, inconsistent hyphenation of a made-up product name — the free tier caught the mechanical errors reliably, and Pro's full-sentence rewrites handled the cases where the sentence was not wrong but was bad: wordy constructions and stiff phrasing came back with genuinely cleaner alternatives. The tone detector, which labels a message as, say, confident or accusatory, remains one of the features I point people to when they ask what this tool is for; in my testing it was accurate often enough to be useful as a second opinion before sending something sensitive.

Second, the everywhere-factor is the real product advantage. In my browser-extension testing the corrections appeared in webmail, in document editors and in support-ticket forms without any setup, and the experience was consistent across surfaces. That sounds mundane and it is exactly what makes the tool hard to displace: the value is not one brilliant feature, it is that the follow-up on writing happens in every text field you touch. The counter-observation: prompt-based generation is metered and thin at free (100 prompts/month) and, while Pro's 2,000 prompts is plenty for rewrites and short drafts, Grammarly is not the tool I would choose for generating a long article from scratch. It is a revising instrument with a generation accessory, not a writing generator with a checker attached.

Notes on the team and admin layer

One area I looked at closely is what Pro actually gives a small team versus what remains Enterprise-only, because the plans page merges what used to be two separate products. Pro includes the team essentials — style guide, brand tones, analytics, user groups — and in my testing a shared style guide did the useful thing: it flagged phrasing that contradicted a house rule across different writers' drafts. What stays behind the Enterprise wall is governance: SAML single sign-on, SCIM provisioning, custom roles, data loss prevention, confidential mode, audit logs and BYOK key management. If you are a regulated buyer, that wall is the decision point, and it is quoted by sales rather than published. For individuals and small teams, the practical takeaway is that Pro is the whole product; the Enterprise column exists for procurement conversations.

What it does not do

Long-form generation is the clear weakness: there is no document-level drafting workflow of the kind writing-specific tools offer, and the generated text in my use reads like competent filler unless you steer it closely. The AI-text and plagiarism detectors are included in Pro, but any detector's accuracy is probabilistic — treat the outputs as signals, not verdicts, particularly in academic settings where false positives have real consequences. On the free tier the generative allowance (100 prompts/month) runs out quickly if you use rewriting as part of every email, and core advanced writing features like full-sentence rewrites are Pro-only. Pricing is per member, so team cost scales quickly: at US$12/member/month annually, a ten-seat team is US$1,440 a year before any Enterprise conversation. Data governance is a genuine consideration — everything you write through the extension is processed by a third party, though Grammarly publishes SOC 2 (Type 2) attestations and Enterprise adds DLP, BYOK and audit controls for regulated buyers. Finally, the corporate story is in motion: the Superhuman merger means the product sits inside a suite being assembled from acquisitions, and suite strategies tend to reshape individual products over time.

Where it sits in my own stack: Grammarly is the tool I leave on, and the one I recommend to people who do not want a writing tool at all. That is a compliment. The proofreader is genuinely good, the friction is genuinely near zero, and for the majority of writing that matters — messages, documents, proposals — the correction and tone layers deliver most of the value before you ever open a prompt box.

Verdict

I rate Grammarly 4.3. On the rubric: core functionality is deep where it matters — the correction engine, tone feedback and rewriting are mature after fifteen years of iteration (40% pillar); value is strong at Pro for individuals and expensive per seat for large teams (20%); usability is the category benchmark, since the tool works in every text field without setup (20%); the ecosystem — extensions, apps, admin controls, integrations, documentation — is the most complete in this category (10%); and reliability signals are strong: a 2009-founded company, published SOC 2 attestation, enterprise governance controls, and a user base large enough that the product is effectively infrastructure (10%). If you want one writing assistant that improves everything you type, this is the safe choice. If you want a long-form content generator, this is not that.

Sources

• https://www.grammarly.com/plans
• https://support.grammarly.com/hc/en-us/articles/115000090011-How-much-does-Grammarly-Pro-cost
• https://grammarly.com/about
• https://grammarly.com/security
• https://en.wikipedia.org/wiki/Superhuman_Platform_Inc.
• https://www.reuters.com/business/grammarly-acquires-email-startup-superhuman-ai-platform-push-2025-07-01
• https://usagepricing.com/blueprint/grammarly
• https://christopherjanb.com/blog/what-is-the-difference-between-premium-and-business-grammarly
• https://cloudeagle.ai/blogs/grammarly-pricing-guide
• https://eesel.ai/blog/grammarly-pricing