Works offline
- Refine with local model
- Yes, after downloading a local model
- Harper
- Yes
Refine vs Harper
Local AI or open-source rules?
Refine with a local model and Harper both check grammar on your device. Refine uses a language model; Harper uses configurable rules.
v1.38
macOS 14+
Free, no account
Quick comparison
| Feature | Refine with local model | Harper |
|---|---|---|
| Works offline | Yes, after downloading a local model | Yes |
| Checking approach | Contextual local AI | Deterministic grammar rules |
| Language coverage | 36 languages, with regional options.See supported languages | English with five dialect settings |
| Price | $38 one-time lifetime license | Free and open source |
Checking approach
- Refine with local model
- Contextual local AI
- Harper
- Deterministic grammar rules
Language coverage
- Refine with local model
- 36 languages, with regional options.See supported languages
- Harper
- English with five dialect settings
Price
- Refine with local model
- $38 one-time lifetime license
- Harper
- Free and open source
Refine vs Harper feature comparison
Both products can check writing locally. The main difference is whether you want contextual AI assistance or a deterministic rule-based checker.
Where checks run
Refine with local model
On your Mac with a downloaded AI model.
Harper
On your device with its local grammar engine.
Private local checks
Refine with local model
Ordinary local checks run on your Mac without uploading the text.
Harper
Harper says its grammar engine uses no telemetry and sends no writing to a server.
Grammar and spelling
Refine with local model
Context-aware grammar and spelling corrections.
Harper
Grammar, spelling, punctuation, and style suggestions from deterministic rules.
Broader writing tools
Refine with local model
Fluency improvements, explanations, translation, and custom prompts.
Harper
Focused on lint messages and suggestions rather than generative rewriting.
Customization
Refine with local model
Custom prompts, instructions, language choices, and model settings.
Harper
Toggle rules, add personal dictionary terms, and extend rules with Weirpacks.
Where you can use it
Refine with local model
Across most Mac apps on macOS 14 or later.
Harper
Browser and editor integrations, plus a system-wide desktop beta for macOS 14 or later on Apple Silicon and Intel.
Price and license
Refine with local model
$38 once for one Mac, or $68 once for 3 Macs.
Harper
Free and open source.
Limits of fixed rule coverage
Where deterministic rules can miss context
A deterministic checker can leave an error unchanged when no matching rule fires. The examples below show the outputs observed in a same-input local check.
Reviewed July 30, 2026. We have not rerun these four selected cases or tested the desktop beta. For each example, we used the same American-English input with both tools, ran the versions shown locally, and compared their outputs with the expected minimal correction. These examples illustrate particular rules and are not an overall accuracy ranking.
Refine v1.34 with Gemma 4 E2B and Harper CLI 2.6.0, both using American English.
What the local check showed
With the same input, the language-model output matched the expected minimal correction. The rule-based checker returned no finding.
Adjective before a noun
The noun “decision” needs the adjective “quick” here, not the adverb “quickly.”
Text to check
The team made a quickly decision before noon.
Expected change
Language model: Caught
Changed “quickly” to “quick.”
Rule-based checker: Missed
No finding; the error stayed unchanged.
Object pronoun after a verb
The pronoun is the direct object of “thanked,” so it needs the object form “her,” not “she.”
Text to check
The courier thanked she for the detailed note.
Expected change
Language model: Caught
Changed “she” to “her.”
Rule-based checker: Missed
No finding; the error stayed unchanged.
Plural subject–verb agreement
The plural subject “doors” takes “have,” not the singular form “has.”
Text to check
The warehouse doors has closed for the night.
Expected change
Language model: Caught
Changed “has” to “have.”
Rule-based checker: Missed
No finding; the error stayed unchanged.
Base verb after a modal
After the modal “must,” English uses the base verb “check,” not “checks.”
Text to check
The driver must checks the mirrors before leaving.
Expected change
Language model: Caught
Changed “checks” to “check.”
Rule-based checker: Missed
No finding; the error stayed unchanged.
Full recorded outputs
Adjective before a noun
- Text to check
- The team made a quickly decision before noon.
- Refine output
- The team made a quick decision before noon.
- Harper output
- The team made a quickly decision before noon.
Object pronoun after a verb
- Text to check
- The courier thanked she for the detailed note.
- Refine output
- The courier thanked her for the detailed note.
- Harper output
- The courier thanked she for the detailed note.
Plural subject–verb agreement
- Text to check
- The warehouse doors has closed for the night.
- Refine output
- The warehouse doors have closed for the night.
- Harper output
- The warehouse doors has closed for the night.
Base verb after a modal
- Text to check
- The driver must checks the mirrors before leaving.
- Refine output
- The driver must check the mirrors before leaving.
- Harper output
- The driver must checks the mirrors before leaving.
Try the sentences in both tools, then compare suggestions on your own writing. Local AI can also make unwanted changes; review each correction before accepting it.
Set up Refine across your Mac appsWhich writing assistant should you choose?
Choose Refine for contextual writing help
Refine is a better fit when you want local AI to understand sentence context and help beyond rule-based grammar.
- You want fluency improvements, explanations, translation, or custom prompts.
- You write in languages beyond English.
- You want one writing assistant across most Mac apps.
Choose Harper for a free, rule-based checker
Harper is a better fit when you want an open-source checker with predictable, configurable rules.
- You prefer deterministic rules over a language model.
- You want browser/editor integrations or the system-wide macOS desktop beta.
- You want a free checker you can inspect and extend.
Refine vs Harper FAQ
Do Refine and Harper work offline?
Yes. Refine checks text locally after you download an AI model. Harper's grammar engine also runs locally.
Do Refine and Harper upload my writing?
With a local model, Refine checks text on your Mac. If you connect a cloud service with your own API key, the text for that task goes to that service. If you send a suggestion report, the original and revised text included in the report go to Refine. Harper says its local engine sends no writing to a server and has no telemetry.
When is Harper a better fit?
Choose Harper for free, open-source English checks with configurable rules. Its macOS desktop beta works across apps; browser and editor integrations are also available.
When is Refine a better fit?
Choose Refine for contextual local AI, multilingual writing, fluency help, explanations, translation, and custom prompts across Mac apps.
Source notes
Harper product details were reviewed September 4, 2026. Product features can change after review.
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v1.38
macOS 14+
Free, no account