Show HN: Charm – on-device spelling, grammar, and prediction for macOS
3 points by theodorehq 5 hours ago | 1 comments
I've spent the last year building Charm, a native macOS menu bar app that corrects spelling, fixes grammar, and predicts your next word.

Three features:

- Spells: NSSpellChecker plus a local LLM for context-aware corrections (catches "definately" -> "definitely" without the false positives macOS autocorrect is known for). - Polish: sentence-level grammar fixes triggered at punctuation boundaries. - Oracle: next-word prediction, Tab to accept.

100% local. Choose Gemma 2 2B or Qwen 2.5 3B; the model downloads once from HuggingFace on first use, then everything runs on your Mac. No cloud option exists, no accounts, no API keys, no telemetry. The model auto-unloads after 5 minutes idle so the RAM cost is bounded.

Built in Swift / SwiftUI. Needs Accessibility and Input Monitoring permissions because text replacement requires reading keystrokes globally. Nothing leaves your machine.

One-time purchase.

I'd love feedback, especially edge cases where corrections go wrong.

  • tradziej 2 hours ago |
    Hey, this looks very good, but could you elaborate more on the grammar corrections? Is it only real-time corrections at the sentence level, or can the tool also be used for multiple-sentence grammar correction and refinement?