Grammarly alternatives

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Each opens with the prompt loaded and waiting — nothing is sent until you press enter. It is copied at the same time, in case the app is not installed.

Build me a local writing assistant I own, to replace Grammarly.

- A web app I run on my own machine: a single Node process serving an editor, documents in a SQLite file next to it.
- Two layers of checking. First, deterministic rules that cost nothing and run on every keystroke: spelling against a local dictionary, doubled words, capitalisation, spacing, passive voice, sentence length, repeated words within a window. Second, an LLM pass (key from .env) that I trigger, for clarity and rewrites.
- Cache the LLM results by paragraph hash so re-checking an unchanged paragraph is free.
- Inline underlines with a click-to-fix popover, and an undo stack.
- A rewrite panel that offers clearer, shorter and more formal versions of a selected paragraph.
- Readability metrics computed locally: word count, average sentence length, Flesch score, longest sentences listed.
- A command-line mode so I can run the same checks over a Markdown file in a repo.
- Runs on localhost only. No accounts, no telemetry. The only thing leaving the machine is the rewrite call, and only when I ask for it.
- Skip: a browser extension, plagiarism checking, and any team features.
- Include a README with setup, where to put the API key, and roughly what a check costs.

## Look and feel

Grammarly's own — clean white, a deep green-teal accent, the text the focus, coloured underlines per problem type, a calm sidebar of cards. Generous spacing, clear hierarchy, big tap targets, phone-readable type, system font. Keep the text dark enough to read at a glance: the softness of a palette belongs to the shapes and the fills, never to the words. Nothing I need to read — dates, numbers, labels — in pale grey on white.