Does grai replace Grammarly?

No. Grammarly fixes grammar, clarity and tone across every app. grai measures whether a draft still matches your own cadence and blocks the ones that do not. One corrects the sentence, the other protects the signature.

Why is a jagged rhythm a feature and not a flaw?

Because it is the part readers recognize. The 134,522-post dataset behind grai shows writers removing the banned vocabulary and keeping a flat metronome rhythm, which is exactly what a clarity engine tends to produce.

How does the cost compare for a team of five?

Grammarly Business for five seats costs about $720 per year and $1,440 over two years. grai Agency is $149 once for 25 client profiles, and the Founder Edition is $69 once for one writer.

Comparison 13 // Voice Ownership vs. Corporate Tone Flattener.

grai vs. Grammarly Business and Pro

Last verified against public pricing and vendor documentation: 2026-10-29.

Direct Answer. Grammarly Pro and Business is a correctness and clarity layer: grammar, tone suggestions and a shared style guide, priced from $12 to $25 per seat per month, which is $144 to $300 per year per seat. grai ($69 once, Founder Edition, or $149 Agency) is a local-first HTML5 voice engine that measures your own cadence and enforces a CV >= 0.32 floor instead of smoothing every sentence toward a corporate register.

Option	Best For	Starting Price	Key Difference
`grai` (Founder)	Keeping a measurable personal cadence while fixing structure before publishing.	$69 once (AI model/API usage separate if used)	622 KB local engine. Voice DNA from 5 to 20 samples, 6 structural rules, `CV >= 0.32` floor, no account.
Grammarly	Teams that need clean grammar, clarity and one shared tone across every document.	$144 per year per seat (Pro, annual billing)	Hosted correctness layer plus a tone and style system. It improves the sentence and flattens the signature.

1. Correctness vs. Voice

Grammarly is excellent at the things that make a sentence correct. It catches agreement errors, simplifies tangled clauses, flags a tone that reads aggressive, and keeps a team consistent through a shared style guide. For a proposal, a contract summary or a customer email, that is exactly the job.

The same smoothing works against a founder's voice. Distinct writing lives in the uneven rhythm: a three-word sentence after a long one, a hard stop where a softer transition would fit. A clarity engine sees those moves as friction and removes them, one harmless suggestion at a time.

grai measures the rhythm before it edits anything. It extracts a profile from 5 to 20 of your posts, then flags the drafts that drift into a flat cadence and shows the exact spans that broke it. The point is not a cleaner sentence. It is a sentence that is recognizably yours.

2. Where Grammarly Wins vs. Where grai Wins

Where Grammarly Wins

Grammar and clarity: the most reliable correctness pass available in a browser and a desktop app.
Tone detection: flags a message that will land badly before you send it.
Team style guide: one set of rules for five or fifty writers.
Coverage: works in email, docs, chat and almost every text field.

Where grai Wins

Measured, not smoothed: a quantitative profile from your own samples, so the gate protects the jagged rhythm instead of removing it.
Deterministic floor: six regex rules plus a CV >= 0.32 burstiness check, computed in JavaScript, with the failed spans listed.
One-time price: $69 once against $144 to $300 per year per seat, which compounds with every seat you add.
Local by default: the text never leaves the browser in the shipped kit, and there is no account to create.

3. Side-by-Side Technical and Commercial Matrix

Criterion	grai (Founder $69 / Agency $149)	Grammarly ($144 to $300 per year per seat)
Pricing model	$69 once (Founder) or $149 once (Agency)	$144 to $300 per year per seat
Primary job	Voice extraction and deterministic cadence verification	Grammar, clarity and tone correction
Effect on rhythm	Preserves it and flags where it broke	Normalizes it toward a clean corporate register
Team scale	One licence per machine; 25 client profiles in Agency	Per-seat licensing, which multiplies with the team
Cadence verification	6 regex rules + `CV >= 0.32` floor, with flagged spans	No sentence-rhythm floor
What happens if you stop paying	You keep `grai.html` and your `.grai` files permanently	Suggestions stop across every surface

4. 12-Month and 24-Month Total Cost Comparison

Setup	Month 1	12-Month Total	24-Month Total	What Is Included
Grammarly Pro, one seat	$12	$144	$288	Grammar, clarity and tone for one writer
Grammarly Business, five seats	$60	$720	$1,440	Shared style guide and admin controls for a team
`grai` Founder + existing AI subscription	$89 ($69 + $20)	$309 ($69 + $240)	$549 ($69 + $480)	Local Voice DNA + Cadence Gate + the model you already use
`grai` Agency Edition (one-time)	$149	$149	$149	25 client Voice Profiles + A4 SHA-256 Client Voice DNA Dossiers

5. Privacy and Data Flow Boundary

Shipped Pre-Built Kit (grai.html): Ships with a Content Security Policy (default-src 'none'; style-src 'unsafe-inline'; font-src data:; img-src data:; script-src 'unsafe-inline'; connect-src 'none'; object-src 'none'; base-uri 'none') that allows inline styles and inline scripts (plus data: fonts and images) while blocking direct API connections (connect-src 'none') from the page. Out of the box, it runs in Copy-Paste mode.
Browser Storage: Voice profiles and writing samples (along with drafts) are stored in your browser's localStorage when available. If your browser settings or private-browsing mode block localStorage on local file:// pages, grai falls back to in-memory session storage (memStorage), which lasts until the tab closes. Export a .grai backup file to save your profiles permanently to disk.
When data leaves your machine: (1) when you paste and submit a prompt into Claude or ChatGPT (or Gemini) in Copy-Paste mode, (2) when you run a custom source build with BYOK enabled and send a prompt to your selected API provider, or (3) when you export and share a .grai file or PDF Dossier yourself. Grammarly sends the text through its own cloud service on every check.

6. Verdict: Which Should You Choose?

Choose Grammarly ($144 to $300 per year per seat) if: correctness and team consistency are the problem. It is the strongest general-purpose clarity layer, and it earns the price.

Choose grai ($69 once) if: your drafts are already clean and still sound like the model. Grammar is not the failure mode; a flat rhythm is.

Use both if: Grammarly handles the final correctness pass and grai gates the cadence before the draft reaches Grammarly. Run the gate first, or the smoothing wins.

Correct the sentence. Do not sand off the voice.

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