Instant Grammar
What Instant Grammar is
Instant Grammar is a free, open-source grammar checker for Windows applications. It uses your OpenAI API key to review selected text and can apply corrections automatically. Suggestions cover grammar, spelling, and writing style, and the checker is intended to work across Windows software such as Word, browsers, and email clients. The download page lists version 1.0.1 for Windows 10 or later and requires 35 MB of free space. The application itself has no subscription charge; you provide the API key and pay OpenAI for usage. Instant Grammar sends text from your device to OpenAI for checking. Its privacy policy says personal text and the locally stored key are not sent to the maker’s servers. Anonymous analytics and crash reports are collected only if you opt in. The project is described as 100% open source, with GitHub access and email support.
Who it suits
It suits Windows users who want grammar, spelling, and style suggestions across multiple applications. Users must have their own OpenAI API key and accept separate OpenAI usage charges.
What it does well
- Free Windows download with no subscription
- Grammar, spelling, and style suggestions
- Works across Word, browsers, and email clients
- Open-source code with GitHub repository
- API key stored locally
What to know first
- Requires Windows 10 or later
- OpenAI usage is billed separately
- Text is sent to OpenAI
- No native macOS or mobile platform listed
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Free | Windows 10 or later | Free |
| Instant Grammar | Free download · no subscription · requires your own OpenAI API key; OpenAI usage billed separately | Free |
As instant-grammar.com lists them, read 21 Sept 2026. The maker's own page has the final word.
Verdict
Instant Grammar combines cross-application checking with automatic corrections and open-source availability. It is most suitable for Windows users comfortable supplying an OpenAI key and paying usage costs separately.
Facts from Instant Grammar's own pages
- Analytics and crash reports
- The privacy policy says the app collects anonymous usage analytics and crash reports only if users opt in. · instant-grammar.com, 11 Oct 2026
- App compatibility
- The site says it works across Windows applications, including Word, browsers, and email clients. · instant-grammar.com, 11 Oct 2026
- Company
- The site copyright notice names Accelio Limited. · instant-grammar.com, 11 Oct 2026
- Corrections
- It offers grammar, spelling, and style suggestions, with corrections applied automatically after text is selected. · instant-grammar.com, 11 Oct 2026
- Desktop app
- Yes · instant-grammar.com, 21 Sept 2026
- Free plan
- Yes · instant-grammar.com, 21 Sept 2026
- Integrations
- The app uses OpenAI's API, and its privacy policy says communication with OpenAI happens directly from the user's device to OpenAI. · instant-grammar.com, 11 Oct 2026
- Local key storage
- The privacy policy says the OpenAI API key is stored locally and never sent to the maker's servers. · instant-grammar.com, 11 Oct 2026
- Open source
- The maker describes the application as 100% open source and links to its GitHub repository. · instant-grammar.com, 11 Oct 2026
- Style suggestions
- Yes · instant-grammar.com, 21 Sept 2026
- Support
- The maker lists support by email at [email protected]. · instant-grammar.com, 11 Oct 2026
- 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. · instant-grammar.com, 11 Oct 2026
- Terms
- The terms say users are responsible for providing their OpenAI API key and paying associated OpenAI usage costs. · instant-grammar.com, 11 Oct 2026
- 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. · instant-grammar.com, 11 Oct 2026
- Usage costs
- No subscription is required; users provide an OpenAI API key and pay OpenAI for usage. · instant-grammar.com, 11 Oct 2026
- What it does
- Instant Grammar is an open source AI-powered grammar checker for Windows applications that uses an OpenAI API key. · instant-grammar.com, 11 Oct 2026
Where Instant Grammar stands on Freedom251
- Grammar checkers#78 of 88