An LLM pass catches most of what Grammarly catches — you're already paying for one. What you can't easily rebuild is the everywhere-ness: the underlines living inside every text box you type into.
VIBE SCORE 72/100
The parts this build actually needs, each rated on its own — the average is the Vibe Score above.
| OS-level integration | 72 |
Don't feel like building it? These are already made, open-source, and free.
Borderline. An LLM pass catches most of what Grammarly catches — you're already paying for one. What you can't easily rebuild is the everywhere-ness: the underlines living inside every text box you type into.
Grammarly costs $12/mo (about $144/yr) as of 2026-08. That's what a working rebuild would save you.
Real-time inline underlining in arbitrary apps means browser extensions and OS-level accessibility APIs — a real project, not a weekend Latency: their suggestions appear as you type; a hotkey flow is a beat slower Team style-guide enforcement across a company
Yes — LanguageTool are open-source options worth trying before you build your own. Details are in the standard parts section on this sheet.