ScriptGrain vs Grammarly

ScriptGrain generates new writing in your measured voice. Grammarly, which most people already have open, corrects the writing in front of it and nudges tone; it does not write as you.

The actual difference

Grammarly corrects the writing in front of it and can nudge tone toward a guide. ScriptGrain measures 45 attributes of how you write and then generates new work constrained to that profile. One improves a draft you wrote; the other writes the draft. That split matters most when a detector gets involved. Correction and generation leave very different fingerprints, and Grammarly is several tools under one brand, so "does it get flagged?" has no single answer. We break down Grammarly and Turnitin properly: what the short answer is, which features change it, and why fixing a sentence isn't the same job as writing one.

Grammarly's paid tier includes one style guide and one brand tone; unlimited requires Enterprise. ScriptGrain's Operator plan is £29/mo for three voice profiles. Note Grammarly's pricing is region-dependent: we saw euros, and you may see a different currency.

ScriptGrain is not a replacement for the assistant you already use. It measures your voice from writing you have published and hands that profile to ChatGPT, Claude, Muse or any MCP client through its connector, then scores every draft against it. ScriptGrain makes your AI better at being you.

How the connector works

Every AI voice tool compared: prices, scores and API access, checked

	ScriptGrain	Grammarly
Entry price	£12/mo (Writer, 1 voice profile)	Pro, €12/mo as displayed to us
Free tier	Yes, See your own voice profile and try one draft. No card.	Yes, permanent. Spelling, grammar, tone detection, 100 AI prompts a month
Voices on entry plan	1 (3 on Operator, £29/mo)	1 style guide and 1 brand tone (Pro)
How the voice is built	45 measured style attributes, extracted from writing you have already published	It builds a voice profile from your writing as you write, continuously, rather than from samples you upload, and keeps separate profiles for documents and messages.

Grammarly figures read from their pricing page on 30 July 2026.

What Grammarly is built for

Grammarly is a writing assistant. It checks grammar, clarity and tone across about a million apps, and that reach is the whole point. You open a browser tab, an email, a document, a chat window, and it's already there, quietly marking the typo before you send.

That's a genuinely hard thing to build, and to be fair, it does it well. It also carries real checking beyond grammar: spelling, plagiarism and AI-text detection, all sitting in the place where you already write. Its parent company rebranded as Superhuman on 2025-10-29, pulling Grammarly, Coda, Superhuman Mail and Go under one name. Read that as a company building a broad productivity suite, with the assistant at the centre of it.

So the job is correction. You write; it improves what you wrote. Everything about the product, from the inline underlines to the tone label, assumes a draft already exists and a human made it.

How Grammarly handles voice

Grammarly's voice features come in two layers, and it helps to keep them apart.

The first is the tone detector. It reads word choice, phrasing, punctuation and capitalisation in real time, in the browser extension, in Office and on the mobile keyboard. It needs 150 or more characters to have anything to say. What it gives back is a tone label, not a number. You see that a message reads as, say, confident or friendly, and you decide whether that's what you meant. Useful, and instant. But a label tells you how a draft lands, not how close it sits to you.

The second layer is brand tones and style guides, which are team features. They push on-brand suggestions at staff as they type. On the Pro plan you get one style guide and one brand tone; unlimited needs Enterprise. The idea is sound: a company writes down its preferences once, and every employee gets nudged toward them without opening a document.

Then there's passive learning. Grammarly builds a voice profile from your writing as you write, continuously, rather than from samples you upload, and keeps separate profiles for documents and messages. Nothing to set up. That's a real advantage.

Grammarly, though, has no published method for scoring a draft against a person's voice. That isn't a criticism of the nudges; they work as nudges. It just means you can't ask "how close is this to me?" and get a number you could check. There's also no public voice or tone API. A Superhuman agents SDK is in private beta, so that may change. As of 2026-09-20, it hasn't.

How ScriptGrain handles voice

ScriptGrain starts somewhere else entirely. It measures.

You give it writing you've already published, and it builds a profile of 45 attributes across 8 layers: lexical, syntactic, tone and register, rhetorical, punctuation and format, function words, content patterns, and quirks and cadence. The attributes are ordinary things you can picture. Average sentence length and how much it varies. Contraction rate. Comma density. Whether you lean on semicolons or dashes. Formality on a 0 to 10 scale. Confidence versus hedging. How you open a piece, how you structure an argument (evidence-first, conclusion-first, narrative), which words tend to start your paragraphs, your mix of I, we and you. The full list is in the writing voice attributes reference.

A profile needs at least one sample of 50 or more words. The recommendation is three or more pieces and about 3,000 words, because more writing gives a steadier read. Extraction usually takes under a minute; the median measured on 2026-09-28 was 39 seconds.

Then comes the part that separates it from a checker. Every draft is scored from 0 to 1 against the profile, a voice match score. On-voice drafts typically land between 0.85 and 0.95. Partial matches sit between 0.5 and 0.8. A clearly different voice comes in under 0.45. The score arrives with per-feature deltas: the draft's value against the profile's value, attribute by attribute. So you don't just learn that a draft is off. You learn it's running at twice your usual sentence length and has dropped every contraction. The method is published in the voice measurement framework, so you can check the working.

Drafts are written with the profile as a constraint. Polish revises a draft toward a target score, 0.9 by default. And the app learns from the edits you save.

One more thing matters for where you work. The profile reaches ChatGPT, Claude, Gemini, Cursor, Meta Muse and any MCP client through the MCP server and the REST API, read live each time. Both are on every plan, Free included. It is never a pasted prompt. If you want the detail, see the API and MCP server page.

The same job in each tool

Take a concrete job. You run a small consultancy and you need a client update email, the kind you've written dozens of times, in your own voice.

In Grammarly, you write it. You open your email, type the draft, and the underlines appear. It fixes a comma splice, flags a long sentence, suggests a tighter phrase. The tone detector, once you pass 150 characters, labels the message. Maybe it reads as formal when you wanted warm, so you soften a line. If your company has set a brand tone, suggestions lean that way too. The result is a cleaner version of what you wrote. The voice in it is yours because you supplied it. Grammarly's contribution is polish and a nudge.

Now the same job in ScriptGrain. The profile already exists from your earlier emails and articles. You ask for the update, through the app or through an assistant like Claude or ChatGPT with the profile read live. A draft comes back written to your measured habits. Then it's scored. Say it lands in the partial band: the per-feature deltas show the opening is too gradual, because you normally lead with the conclusion, and the sentences run longer than yours. Polish revises toward 0.9, and you edit the rest. Your saved edits feed back into the profile.

Different starting points, different strengths. If the email is nearly written and needs cleaning, Grammarly is the faster route. If you'd rather not write it from nothing, or you need forty of them in a consistent voice, the measured route is what you want. You can see the countable part of your own style with the free writing style analysis tool.

Which one fits which situation

The honest answer depends on whether your problem is correctness or identity.

Pick Grammarly if:

You write your own drafts and mainly want them clean, across every app you use.
You want a voice nudge with no setup and no samples to gather.
A free tier that actually does something matters to you.
Your team needs one shared style guide and brand tone enforced as people type, and Pro's one of each covers it.

Pick ScriptGrain if:

You want new writing generated in your voice rather than corrected after the fact.
You need a number for voice match and the attribute-level reasons behind it.
You manage several voices, your own and clients', and need them kept apart.
You work through AI assistants and want your profile applied to whatever they produce.

And sometimes both. If you generate in a measured voice and then send it out through email and documents where Grammarly already sits, there's no conflict. One produces the draft; the other catches the stray typo on the way out. So the real question is seldom either/or.

Using ScriptGrain alongside Grammarly

Running both is simple, because they sit at different points in the job.

Generate first. Build your profile from your published writing, then draft through ScriptGrain, directly or via an assistant that reads the profile live. Check the score and the deltas. Polish toward your target. By then the draft sounds like you.

Then let Grammarly do what it does best. Paste or send that draft through the apps you already live in and take the spelling, grammar and clarity suggestions that genuinely help. Be a little careful here. Grammarly's tone nudges are aimed at a general standard or a team guide, not at your measured profile, so a suggestion can pull a sentence away from your habits. Accept the corrections; weigh the tone edits. If a change drops a contraction you'd always use, your deltas will show it on a recheck, and that's a useful way to catch voice drift.

If you're moving from Grammarly rather than adding to it, there's little to migrate, since Grammarly's profile builds passively inside its own tools and isn't something you upload from. Start with your best published pieces in ScriptGrain and keep Grammarly for the checking. For a wider view of where each tool sits, the comparison matrix lays the category out, and pricing has the plan detail.

Grammarly's prices display by region, and you may see a different figure from the one we read. Check your own screen before you decide.

Where Grammarly is stronger

The default writing assistant for most people, and the only tool here that learns your voice passively.

Passive learning: nothing to upload, the profile builds itself as you type
A genuinely useful free tier, which most of this category no longer offers
Grammar and clarity checking that ScriptGrain does not attempt at all
Works everywhere you already write, via the browser and desktop apps

If what you want is grammar and clarity checking across every app you use, Grammarly does that well and ScriptGrain does not do it at all. They solve different problems and plenty of people should have both.

Questions

Is ScriptGrain better than Grammarly?

They solve the problem differently. Grammarly corrects the writing in front of it and can nudge tone toward a guide. ScriptGrain measures 45 attributes of how you write and then generates new work constrained to that profile. One improves a draft you wrote; the other writes the draft. That split matters most when a detector gets involved. Correction and generation leave very different fingerprints, and Grammarly is several tools under one brand, so "does it get flagged?" has no single answer. We break down Grammarly and Turnitin properly: what the short answer is, which features change it, and why fixing a sentence isn't the same job as writing one. If what you want is grammar and clarity checking across every app you use, Grammarly does that well and ScriptGrain does not do it at all. They solve different problems and plenty of people should have both.

How much does Grammarly cost compared with ScriptGrain?

Grammarly's entry plan is Pro, €12/mo as displayed to us, with this free tier: Yes, permanent. Spelling, grammar, tone detection, 100 AI prompts a month. ScriptGrain starts at £12/month (Writer, 1 voice profile) with a free plan: See your own voice profile and try one draft. No card. Grammarly figures read from their pricing page on 30 July 2026.

Does Grammarly learn my writing voice?

It builds a voice profile from your writing as you write, continuously, rather than from samples you upload, and keeps separate profiles for documents and messages. ScriptGrain instead measures 45 style attributes from writing you have already published, and scores every draft against that measured profile.