SMF·GRAMMARLY
Can a prompt replace Grammarly?
AI writing — writing assistant
Exhibit tracking slip
Verdict
Grammar checking itself is a solved, open-source problem, and wiring it to an LLM for tone rewrites is a real weekend build. What doesn't come with it is Grammarly's actual product: suggestions appearing inline inside every app you already write in, not a separate page you paste text into.
Exhibit A — The prompt
Received on30.07.2026Build a personal writing checker around LanguageTool, an open-source grammar and style engine you can run locally via its official Docker image — grammar checks never have to leave your machine. Build a small page where you paste text and see LanguageTool's issues underlined with hover explanations and click-to-apply suggestions. Add an LLM-powered rewrite pane with a few fixed options (tighten, friendlier, more formal) that shows a diff against the original before anything is applied — never silently overwrite the source text. Support a personal dictionary file of names and jargon that should never be flagged, passed into every check. Add a command-line mode that checks a file and exits non-zero on any issue, so it can run as a pre-commit hook on documentation.
Do not build a browser extension or inline suggestions inside Gmail, Docs, or Slack — that cross-app integration is real, ongoing platform work, and this build is honestly a destination you paste into, not a layer over everything else.Opening prefills the prompt — press enter to run it.
Exhibit B — What you lose
- B.1 inline suggestions inside Gmail, Docs, Slack, and everywhere else you write
- B.2 tone and brand controls tuned for an organization
- B.3 years of tuning down false-positive suggestions
- B.4 enterprise admin controls
Prior art
Exhibit C — Why people still pay: cross-app integration/model quality
The value is suggestions appearing inside the apps where writing actually happens — a destination you paste into is a real downgrade from that, even with equally good grammar checking underneath.
Questions
Can I bring over anything from my Grammarly account?
Not really — Grammarly doesn't export your personal dictionary or writing style settings. Rebuilding your ignore-list of names and jargon is quick, but it starts from scratch.
Will it work on my phone?
As a page you paste text into, technically yes, but there's no inline suggestion layer and no keyboard integration — on mobile specifically, that gap is much more noticeable than on desktop.
What does it cost to run?
Hosting for LanguageTool, which wants roughly a gigabyte of memory, plus optional LLM API usage for the rewrite feature — a few dollars a month either way.
What's the one thing that doesn't survive the rebuild?
Writing where you already write. Grammarly's suggestions appear inside Gmail, Docs, and Slack as you type; this build only ever sees text you've copied somewhere else first.
Related tools
Receipt