Grammarly vs QuillBot extension review: privacy score, data collection & safer alternatives
Incogni's 2026 study flags Grammarly and QuillBot as high-risk AI extensions. Privacy analysis, permission breakdown, and safer alternatives for 2026.
There's a good chance you're reading this with Grammarly or QuillBot running in your browser right now. Between them, these two AI writing assistants have tens of millions of active installs. And the vast majority of those users have never thought twice about what the extension can see while it's helping them write.
That's the real question here. Not "are these extensions malware?" — they're not. But Incogni's 2026 annual study, which analyzed 442 AI-powered Chrome extensions, ranked both among the most potentially privacy-risky popular extensions in their dataset, as reported by HelpNetSecurity. If you use either tool daily, this review is worth reading before your next install.
TL;DR verdict
Grammarly — Broad host permissions, data sent to company servers for processing, usage data collected. Ranking: among highest-risk popular AI extensions in Incogni's 2026 methodology. Legitimate tool. Privacy trade-off is significant.
QuillBot — Similar permission scope. Also flagged by Incogni's 2026 study. Useful for paraphrasing. Similar privacy trade-offs apply.
Bottom line: If you're okay with an extension reading everything you type in your browser, either tool works as advertised. If that scope of access concerns you, this article covers alternatives.
What these extensions do
Grammarly checks spelling, grammar, tone, and clarity as you type — across Gmail, Docs, websites, and most text fields in your browser. QuillBot rewrites and paraphrases text, offering several output modes from formal to casual. Both work by reading what you're typing in real time, sending it to their servers for analysis, and returning suggestions.
This is not a bug or a hack. It's how the product works. The privacy considerations stem from what that access model necessarily requires — not from any documented misuse.
Permissions they request
Both extensions request the ability to read and modify data on all websites you visit. In Chrome's permission model, that means <all_urls> host permissions — the broadest access available. It allows the extension to read the content of any page, including what you're typing into login forms, email drafts, internal tools, and financial portals.
They also use scripting APIs to inject their interface directly into web pages. Incogni's 2026 study found that 42% of AI extensions require scripting permissions, affecting an estimated 92 million users across the dataset. Grammarly and QuillBot are both in that 42%.
None of this is hidden. Chrome's permissions dialogue describes it clearly. The problem is that most users click through installation prompts without reading them — and "reads and changes all your data on all websites you visit" doesn't sound alarming until you think about what sites you actually visit.
What the Incogni 2026 study found
Incogni's 2026 privacy research analyzed 442 AI-powered Chrome extensions across eight categories. The study found that 52% of AI extensions collect user data, and 29% collect personally identifiable information. Ten extensions in the dataset were identified as having both high risk likelihood and high risk impact.
HelpNetSecurity's coverage of the study reported that Grammarly and QuillBot were among widely used Chrome extensions facing serious privacy questions under Incogni's methodology. Incogni's study ranked programming and mathematical aid extensions as posing the greatest average privacy risk by category.
To be clear about what this means: Incogni's methodology evaluates risk potential based on permissions and stated data practices. Being ranked high-risk by their methodology doesn't mean your data is being misused — it means the structural access these extensions hold creates meaningful privacy exposure. Neither Grammarly nor QuillBot has publicly responded to Incogni's specific 2026 findings as of March 2026, as far as I'm aware.
What data actually gets collected
Grammarly's publicly available privacy documentation states that it collects the text you choose to check, usage data, and device information. Writing samples may be used to improve their AI models — enterprise plans include options to opt out of this. Content is transmitted to Grammarly's servers for processing. Their privacy policy is detailed and publicly accessible.
QuillBot's privacy documentation follows a similar pattern: text you submit is processed on their servers. Their documentation indicates retention of data for product improvement with opt-out available.
Both companies are transparent about this in their terms. The issue isn't opacity — it's that most users install browser extensions without ever opening the privacy policy. There's a meaningful gap between "the information exists" and "users are informed." I definitely fell into that gap myself before building Extenshi.
If you're using either extension in a work context that involves client data, legal documents, healthcare information, or anything confidential, you're routing that content through a third-party commercial service by default. Enterprise Grammarly plans offer stronger data isolation and contractual protections — but most users are on free or individual plans.
Checking the current security profile
Extension permissions and data practices can change across versions. An update that quietly adds a new permission or expands data collection scope won't surface automatically unless you're tracking it.
You can check the current permission profile and security scan for both extensions on Extenshi's catalog:
- Search Grammarly on Extenshi catalog — view current permissions and scan data
- Search QuillBot on Extenshi catalog — compare access scope and data handling flags
- Browse all AI writing extensions — see how they stack up by permission breadth
The catalog tracks permission changes across extension versions, so if either tool expands its access in a future update, there's a record of what changed.
Safer alternatives
If reading everything you type across all websites feels like more access than you want to hand to a commercial service, a few alternatives work differently.
LanguageTool is open-source, and its browser extension sends text to their servers by default — similar to Grammarly. But unlike any major commercial grammar tool, you can self-host LanguageTool's backend and point the extension at your own server. That keeps your text entirely off third-party infrastructure. The interface is less polished and the AI suggestions aren't as advanced as Grammarly, but it's a real option for privacy-first users.
Hemingway App works as a desktop application, not a browser extension. There's no data leaving your machine. You paste text in, get readability feedback, and leave. It doesn't do grammar in the same way, but for clarity editing it's genuinely useful — and completely offline by design.
Vale is a command-line linter for prose that runs locally. It's built for developers and technical writers who work in editors like VS Code. Way more friction than Grammarly, but zero data transmission.
Google Docs built-in spelling and grammar is worth a mention. If you're already in Docs, the native check doesn't add another party to the data flow beyond Google — and you're already trusting Google if you're using Docs. Less capable than Grammarly, but one fewer commercial relationship in the loop.
None of these alternatives match Grammarly's inline editing experience across every website and text field. That seamless integration is exactly why Grammarly has tens of millions of installs. The trade-off is real: more integration means more access.
Final recommendation
If you use Grammarly or QuillBot for personal writing and your content isn't sensitive, the risk is bounded and the tools are functional. These are not malicious extensions. But the access they require is among the broadest any extension category holds.
If your use case involves anything confidential — client work, legal review, medical documentation, proprietary business information — the default setup of either tool deserves more scrutiny. Enterprise plans include tighter controls; free and personal plans route everything through shared infrastructure.
The honest answer for most users: the risk is structural rather than operational. You're trusting the company's data practices, not their code. For that to be a conscious decision rather than a default one, you need to know what you're agreeing to.
See security reports for AI writing extensions →
This article is based on publicly available security research and news reporting. Extenshi does not independently verify all claims made by third-party researchers. References to specific companies or products reflect the findings of cited sources and do not constitute accusations of intentional wrongdoing. If you believe any information is inaccurate, please contact us at [email protected].
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