Instant Grammar

6.1easy start · #75of 88
in Grammar checkers

Free to practise onyes
Well documentedno
Runs where you workno

Runs on Windows.

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Instant Grammar is ranked #75 of 88 in grammar checkers on The Geeks Club. It runs on Windows. There is a free plan.

Instant Grammar plans and pricing

All plans

Free Free Windows 10 or later instant-grammar.com · 21 Sept 2026

Instant Grammar Free Free download · no subscription · requires your own OpenAI API key; OpenAI usage billed separately instant-grammar.com · 11 Oct 2026

Compared on grammar checkers

Free plan: Yes
Desktop app: Yes
Style suggestions: Yes

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The record

What it does: Instant Grammar is an open source AI-powered grammar checker for Windows applications that uses an OpenAI API key.
Corrections: It offers grammar, spelling, and style suggestions, with corrections applied automatically after text is selected.
App compatibility: The site says it works across Windows applications, including Word, browsers, and email clients.
Open source: The maker describes the application as 100% open source and links to its GitHub repository.
Usage costs: No subscription is required; users provide an OpenAI API key and pay OpenAI for usage.
Supported version: The download page lists version 1.0.1 for Windows 10/11 and requires Windows 10 or later with 35 MB of free space.
Integrations: The app uses OpenAI's API, and its privacy policy says communication with OpenAI happens directly from the user's device to OpenAI.
Text handling: The privacy policy says personal text is not stored or transmitted to the maker's servers, while the app sends text to OpenAI for grammar checking.
Local key storage: The privacy policy says the OpenAI API key is stored locally and never sent to the maker's servers.
Analytics and crash reports: The privacy policy says the app collects anonymous usage analytics and crash reports only if users opt in.
Support: The maker lists support by email at [email protected].
Terms: The terms say users are responsible for providing their OpenAI API key and paying associated OpenAI usage costs.
Company: The site copyright notice names Accelio Limited.
Price from: Free

Where it ranks on The Geeks Club

Best Grammar Checkers in 2026#75 of 88

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Sources

instant-grammar.com· checked 11 Oct 2026
instant-grammar.com/privacy· checked 11 Oct 2026
instant-grammar.com/terms· checked 11 Oct 2026