ScriptGrain vs EigenVox

ScriptGrain measures your voice across 45 attributes and holds every draft to it across sixteen content types, with an API and MCP server. EigenVox is the closest peer, also genuinely stylometric, built as a focused single-purpose tool rather than a platform.

The actual difference

This is the one comparison where the honest answer is not "they describe, we measure", EigenVox measures too. The difference is scope: ScriptGrain covers sixteen content types with a public API and MCP server so the profile can sit inside your own tooling.

EigenVox starts individuals with a $1 card verification and $5 of credit, and prices Teams at $199 per principal a month during a pilot programme. ScriptGrain publishes its plans: free to see your own profile, £12/mo for one profile, £29/mo for three.

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	EigenVox
Entry price	£12/mo (Writer, 1 voice profile)	$1 card check, then $5 credit (individual)
Free tier	Yes, See your own voice profile and try one draft. No card.	None
Voices on entry plan	1 (3 on Operator, £29/mo)	Not published
How the voice is built	45 measured style attributes, extracted from writing you have already published	They "extract the stylometric fingerprint hidden in your prose" from a sample of at least 500 words, analysing "phrases you favor, how you build sentences, and the rhythm that's recognizably yours". Generated output is "scored against your fingerprint and reranked before you see it", finishing with a polish pass aimed at removing flat, over-edited AI tone. On Teams, each client gets a ship threshold: drafts that score below it never reach the client.

EigenVox figures read from their pricing page on 30 September 2026.

What EigenVox is built for

EigenVox does one job. It takes your writing, builds a fingerprint from it, and makes sure what a machine writes for you sounds like you. That's the whole pitch: "Machines will write most of your words. They should still be yours."

Most tools stop at the fingerprint. The harder bit comes after: wiring it into your actual process, so briefs, drafts and edits all pull in the same direction and you stop rewriting every paragraph by hand. We've written up that whole setup in an AI content workflow built to keep your voice intact. It covers where generic output creeps in, and how to catch it early.

So it's a focused tool, not a platform. And to be fair, that focus shows in how it's aimed. Individuals can start with a $1 card verification and $5 of credit, which is about as low a bar as you'll find. Teams is pitched at agencies and ghostwriters, under the line "One team. Thirty principals. Every voice provable." Think of someone juggling many clients, each with a distinct way of putting things, who needs to keep them apart and show the work. On Teams, client material stays separate per principal, and editor seats are unlimited.

We read those pages on 2026-09-30, and that's the date for anything quoted here. Teams was $199 per principal a month during a pilot programme at that point. Pilot pricing moves, so check it before you budget around it.

The short version: EigenVox is for people who want to write, rewrite or expand from bullets, inside one product, with voice enforced on the way out.

How EigenVox handles voice

Here's how it works. You paste writing samples, 500 words minimum, and more is better. EigenVox analyses them and builds what it calls a voice fingerprint: the phrases you favour, how you construct sentences, the rhythm that's recognisably yours.

Then you generate. Write from scratch, rewrite something, or expand a set of bullets. Every output carries a VoiceMatch score, and each draft is reranked against the fingerprint before you see it. A final polish pass strips out generic phrasing. EigenVox says it measures against your fingerprint, "not against AI detectors", which is a sensible distinction to draw.

The part worth dwelling on is enforcement. On Teams, each client gets a ship threshold. A draft that scores below it never reaches the client. That's a real control, and it moves quality checking from "someone should read this" to "the system won't let weak work through". For an agency with thirty voices, that matters.

Two things EigenVox doesn't publish: the VoiceMatch formula, and a list of the features it measures. You see a score; you can't see what it's made of. Whether that bothers you depends on how much you need to explain a score to a client or an editor. Its pages mention no API or MCP server, so the fingerprint lives inside EigenVox.

How ScriptGrain handles voice

ScriptGrain starts from the same idea (measure, don't describe) and goes wider on scope and transparency.

A profile is built from writing the person or brand has already published. It holds 45 attributes in 8 layers: lexical, syntactic, tone and register, rhetorical, punctuation and format, function words, content patterns, and quirks and cadence. Examples are concrete. 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, whether evidence-first, conclusion-first or narrative. Paragraph openers. Pronoun mix. The full list sits in the writing voice attributes reference.

The sample bar is higher than EigenVox's in one sense and lower in another. One sample of 50 or more words is enough to begin; three or more pieces and about 3,000 words is the recommendation. Extraction usually takes under a minute (median 39 seconds, measured 2026-09-28).

Every draft is then scored from 0 to 1 against the profile. 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 the draft's value against the profile's value: sentences running long, hedging creeping in, dashes that shouldn't be there. The method is published in the voice measurement framework.

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

The profile also travels. Through the MCP server and the REST API, it reaches ChatGPT, Claude, Gemini, Cursor, Meta Muse and any MCP client, read live each time. Both are on every plan, Free included. It is never a pasted prompt.

The same job in each tool

Take one job: a founder wants a launch announcement in her own voice, and she has a pile of published posts to work from.

In EigenVox, she pastes the posts (comfortably past 500 words), and the fingerprint forms. She drops in a few bullets about the launch and asks it to expand. Out comes a draft with a VoiceMatch score, already reranked, already polished. If the score is high, she ships it. If she's on Teams with a threshold set, a weak draft simply doesn't arrive. The loop is tight, and it all happens in one place.

In ScriptGrain, she adds the same posts and gets a profile. She might then draft in Claude, with the profile read live through MCP, and have the result scored. Say it lands in the partial-match band. The deltas show her why: the draft's sentences run longer than her profile's, and it hedges where she states things flat. She runs polish toward 0.9, or fixes those two things by hand. The draft she was already writing in another tool stays where it was.

Same job, different shape. EigenVox gives you a finished, scored draft inside its own walls. ScriptGrain gives you a measurement that follows you into the tools you already use, and tells you what's off in specific terms. Neither is wrong. They suit different habits.

One caution on the scores. They aren't comparable. EigenVox's VoiceMatch and ScriptGrain's voice match are separate formulas on separate scales, and only one of the two publishes how it's built. Don't read a number from one as a verdict on the other.

Which one fits which situation

Some situations are easy to call.

You want the lowest-friction start and a single place to write. EigenVox. 500 words, a $1 card check, and you're generating. That's a genuinely low bar.
You run an agency or ghostwriting shop with many principals and need hard gating. EigenVox deserves a serious look. A per-client ship threshold that blocks weak drafts, with material kept separate per principal, is built for exactly this.
You write inside ChatGPT, Claude, Cursor or your own tooling and want the same voice everywhere. ScriptGrain. The profile is read live through MCP and the API, so it isn't locked to one editor.
You need to see why a draft missed. ScriptGrain. Per-feature deltas and a published method give you something to act on, and something to explain to someone else.
You write across many formats. ScriptGrain covers sixteen content types, from the same profile.
You want to try before paying. ScriptGrain's Free plan gives you one profile and one full analysis with no card. EigenVox needs the $1 verification first.

If you're mostly one person writing mostly in one place, the gap narrows, and preference wins. Pick the workflow you'll actually use.

Using ScriptGrain alongside EigenVox

Using both is reasonable, and there's a clean way to split the work.

Suppose an agency runs its client drafts through EigenVox for the ship threshold, since that gate is the thing it does best. The same agency might also keep ScriptGrain profiles for those clients' voices, so that drafts started in Claude or ChatGPT arrive already close. You'd be using ScriptGrain for where the writing starts and EigenVox for the gate at the end. A cross-check helps too: run a finished piece through the brand voice consistency checker and see whether the deltas agree with what EigenVox's score implies.

A few practical notes.

Build each profile from the same source writing. If the samples differ, the two tools will measure two slightly different people.
Don't compare raw scores. Use each one inside its own scale, and treat disagreement as a prompt to look at the text.
Decide which tool is the gate. Two gates mean two sets of edits, and they'll pull against each other. Pick one as final.
Keep the profile live. Because ScriptGrain's profile is read at the point of use, updating it once updates it everywhere, which suits a setup where several tools touch the same draft.

For a wider view of how the category splits, the AI writing voice tools matrix sets the options side by side. And if neither fits, /vs lists the other comparisons.

That's the honest read. EigenVox is a sharp, narrow tool that does its narrow job well. ScriptGrain is wider, and shows its working.

Where EigenVox is stronger

A focused stylometry tool: extract the fingerprint in your prose, then generate against it. The closest thing to a direct peer in this comparison set.

Genuine stylometry, not tone sliders, they measure and they score, which most of this category does not
Scoring and reranking happen before you see the draft, so the measurement is enforced rather than advisory
A focused single-purpose tool: less to learn if all you want is styled output from samples

If you want the simplest possible route from a few writing samples to styled output, with no wider platform attached, EigenVox is a fair choice and does the core thing properly. We would rather say that than pretend the category has only one serious measurement-based tool in it.

Questions

Is ScriptGrain better than EigenVox?

They solve the problem differently. This is the one comparison where the honest answer is not "they describe, we measure", EigenVox measures too. The difference is scope: ScriptGrain covers sixteen content types with a public API and MCP server so the profile can sit inside your own tooling. If you want the simplest possible route from a few writing samples to styled output, with no wider platform attached, EigenVox is a fair choice and does the core thing properly. We would rather say that than pretend the category has only one serious measurement-based tool in it.

How much does EigenVox cost compared with ScriptGrain?

EigenVox's entry plan is $1 card check, then $5 credit (individual), 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. EigenVox figures read from their pricing page on 30 September 2026.

Does EigenVox learn my writing voice?

They "extract the stylometric fingerprint hidden in your prose" from a sample of at least 500 words, analysing "phrases you favor, how you build sentences, and the rhythm that's recognizably yours". Generated output is "scored against your fingerprint and reranked before you see it", finishing with a polish pass aimed at removing flat, over-edited AI tone. On Teams, each client gets a ship threshold: drafts that score below it never reach the client. ScriptGrain instead measures 45 style attributes from writing you have already published, and scores every draft against that measured profile.