# grai vs. Grammarly Business and Pro: $69 Once vs. $144 to $300 per Year (2026)

> **Last verified against public pricing and vendor documentation:** 2026-10-29
> **Canonical URL:** https://grai.page/vs/grammarly

**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.

### TL;DR Comparison

| 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.

---

## Frequently Asked Questions

### 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.

**Checkout:** [Founder Edition ($69 once)](https://payhip.com/b/5pXfN) | [Agency Edition ($149 once)](https://payhip.com/b/QVIBp)