ScriptGrain vs Copy.ai

ScriptGrain gives you a measured voice profile you can inspect, refine with more samples, and re-check over time. Copy.ai infers a voice from a sample and keeps its reasoning to itself.

The actual difference

Copy.ai analyses a sample to infer a voice. ScriptGrain produces a measured 45-attribute profile you can inspect, compare and re-check over time: the analysis is the product, not a hidden step.

Copy.ai's Chat plan is $29/mo, and the next self-serve plan is Growth at $1,000 a month billed annually. ScriptGrain's ladder runs £12 to £299 with every step public.

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

ScriptGrainCopy.ai
Entry price£12/mo (Writer, 1 voice profile)$29/mo (Chat)
Free tierYes, See your own voice profile and try one draft. No card.None
Voices on entry plan1 (3 on Operator, £29/mo)No Brand Voice count stated for any self-serve plan on the pricing page
How the voice is built45 measured style attributes, extracted from writing you have already publishedPaste at least 300 words of existing content, click Analyze Brand Voice, review, then pick that voice when generating.

Copy.ai figures read from their pricing page on 30 September 2026.

What Copy.ai is built for

Copy.ai no longer describes itself as a writing tool. Its own pricing page calls it "the world's first GTM AI platform," aimed at sales, marketing and operations workflows (read 2026-09-30). That positioning matters more than any feature list, because it tells you who the product is being shaped for.

So here's the honest read. Copy.ai is built for go-to-market teams that want work to move through a stack: a lead comes in, research happens, an email gets drafted, something gets routed. Writing is one step in that chain. The unit of value is the workflow, and the pricing reflects it. Growth, Expansion and Scale are built around workflow credits and seat counts, not around how closely a paragraph resembles one particular person.

That's a real strength, and to be fair, it's not a small one. If your problem is "we have a sales team of dozens and want repeatable automation," you are in Copy.ai's territory. If your problem is "my newsletter stopped sounding like me," you're reading a product that has moved its attention elsewhere.

One more detail worth holding onto for later. The lower rungs still exist. The Chat plan is a self-serve way in, with unlimited chat words and access to OpenAI, Anthropic and Gemini models. It's a perfectly reasonable place to write. It just isn't where the company's ambition sits.

How Copy.ai handles voice

Copy.ai's Brand Voice feature is simple to describe. You paste examples of your best content (blog posts, social posts, emails), click "Analyze Brand Voice," review what comes back, and then pick that voice when you generate. Copy.ai recommends 300 or more words of input, and you can build separate Brand Voices for separate audiences (source: copy.ai/features/brand-voice, read 2026-09-20).

There's a lot to like in that. The setup is fast. The mental model is obvious. Building one voice per audience is a sensible way to handle a company that talks differently to buyers and to developers.

The analysis, though, is a closed step. Copy.ai publishes no method for it, and there's no inspectable score or attribute list that comes out the other side. You get a voice you can select. You don't get a description of what that voice contains, so you can't check which habits were captured, which were missed, or whether a draft three months from now has wandered off.

In practice, that means your quality control is your own ear. You read the output, decide it sounds right, and move on. For a solo writer who knows their own voice cold, that can be enough. For a team where five people review copy and none of them agrees on what "on brand" means, it's thinner ground.

No Brand Voice count is stated for any plan on the pricing page (read 2026-09-30).

How ScriptGrain handles voice

ScriptGrain treats the analysis as the product. It measures a writing voice from writing the person or brand has already published, and the result is 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 full list sits in the writing voice attributes reference.

What does an attribute look like? Average sentence length and its variance. Contraction rate. Comma density. Semicolon and dash habits. Formality on a 0 to 10 scale. Confidence versus hedging. Opening style. Argument structure (evidence-first, conclusion-first, narrative). Paragraph openers. Pronoun mix. These are things you can read, argue with and edit.

A profile needs at least one sample of 50 words or more. The recommendation is three or more pieces and about 3,000 words, because a voice is easier to pin down when you see it across different topics. Extraction usually takes under a minute; the median measured on 2026-09-28 was 39 seconds.

Then comes the part that changes the workflow. Every draft is scored from 0 to 1 against the profile, which is the voice match. 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, so you see draft value against profile value: sentences running longer than the profile says, say, or a contraction rate that has slipped. The method is published in the voice measurement framework.

Polish revises a draft toward a target score (the default is 0.9). Drafts are written with the profile as a constraint, and the app learns from the edits a user saves. And 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, including Free. It is never a pasted prompt.

The same job in each tool

Take one job and run it twice. A founder writes a monthly customer update in a dry, direct style. Short fragments. Few adjectives. Conclusion first. She wants a new one every month without rewriting it from scratch.

In Copy.ai, she pastes a few past updates into Brand Voice, clicks Analyze Brand Voice, and reviews the result. She selects that voice and generates a draft. It reads plausibly like her. She edits the parts that feel off, using her own ear, and sends it. Next month she repeats the generation. If the tone has crept towards something chattier, she notices only if she happens to read closely that day. There's no number telling her, and no way to say which habit moved.

In ScriptGrain, she adds the same updates and gets a profile in under a minute. She reads it: average sentence length sits low, variance is high, conclusion-first is the dominant argument structure, and hedging is rare. She edits one attribute that looks off. The draft comes back scored. Suppose it lands in the partial band. The deltas show that sentences have drifted longer and openers have become generic. Polish pulls it toward the target. She saves her edits and the profile learns from them.

Three months on, she runs the old profile against a new draft and can see voice drift as a measurable gap rather than a vague unease. That's the difference in practice. Both tools get her a draft. Only one gives her something to check it against.

And to be fair to Copy.ai, if she just wants a decent first pass and trusts her own editing, the extra measurement adds little for this one task. The gap opens over repetition and over people.

Which one fits which situation

Pick based on the job, not the brand name. Here's how it tends to split.

Whichever tool you pick, most of what gets called slop has the same cause: nobody's voice sits behind the sentence, so nobody stands by it. If that's your problem, our argument that AI slop is a voice problem explains why flat tone and recycled structure are only symptoms, and why the fix starts somewhere other than using less AI.

Price shapes the choice too, though the table already covers it. Copy.ai's self-serve ladder jumps from the Chat plan to Growth, which is a big step. ScriptGrain's ladder runs from Free through £12 to £299, with every step public. If you sit between "one person" and "a 75-seat GTM team," that gap is worth noticing.

Using ScriptGrain alongside Copy.ai

Using both is a legitimate setup, not a fudge. The split is clean: Copy.ai runs the workflow, ScriptGrain defines and checks the voice.

Here's how that tends to work. Build the profile first. Take your best published writing, let ScriptGrain measure it, and read the result. Then use it as the standard against which anything Copy.ai produces gets checked. A draft generated in Copy.ai can be scored against the profile, and the deltas tell you where it wandered. If a team member asks why a piece feels off, you have an answer that isn't "it just does."

Moving over is less dramatic than it sounds. Nothing stops you keeping Copy.ai's Brand Voices in place while you build the profile alongside them. Your source material is the same either way: published writing, ideally three pieces or more and around 3,000 words. Run both for a few weeks and compare what each gets right.

A couple of practical notes. Keep the samples honest: pick writing you'd genuinely want more of, not just whatever's recent. Re-check the profile when your style shifts on purpose, since a rebrand or a new audience changes the target. And if you're working from a public website, brand mimic can build a profile from it, but only with explicit consent that you own or may use the site.

If your team uses ChatGPT or Claude day to day, the ChatGPT and Claude pages explain how the live read works. For anyone who wants to see how the wider field compares, the tools matrix lays it out.

At the end of the day, this isn't a fight to the death. One tool moves work through a stack. The other measures the thing your readers actually notice. Plenty of teams need both, and the trick is knowing which question you're asking at the time.

Where Copy.ai is stronger

Has moved decisively upmarket into a "GTM AI platform": the self-serve Chat plan, then Growth, Expansion and Scale at $1,000 to $3,000 a month billed annually, then Enterprise.

For a GTM team wanting workflow automation across many seats, Copy.ai is built for that and ScriptGrain is not.

Questions

Is ScriptGrain better than Copy.ai?

They solve the problem differently. Copy.ai analyses a sample to infer a voice. ScriptGrain produces a measured 45-attribute profile you can inspect, compare and re-check over time: the analysis is the product, not a hidden step. For a GTM team wanting workflow automation across many seats, Copy.ai is built for that and ScriptGrain is not.

How much does Copy.ai cost compared with ScriptGrain?

Copy.ai's entry plan is $29/mo (Chat) ($24/mo billed annually ($288 a year)), with no free tier. ScriptGrain starts at £12/month (Writer, 1 voice profile) with a free plan: See your own voice profile and try one draft. No card. Copy.ai figures read from their pricing page on 30 September 2026.

Does Copy.ai learn my writing voice?

Paste at least 300 words of existing content, click Analyze Brand Voice, review, then pick that voice when generating. ScriptGrain instead measures 45 style attributes from writing you have already published, and scores every draft against that measured profile.

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