What a voice profile measures (and what it can't)
NEO's voice profile is a numeric fingerprint of how you write, built from a sample of your real writing and stored only on your device. Here's exactly what goes into it, how to build a good one, and — just as important — what the numbers can't tell you.
The five measurements
Average sentence length. Some writers think in 12-word bursts; others build 25-word structures. Neither is better — but a draft that's 10 words off your average won't sound like you.
Rhythm (sentence-length variation). How much you mix short and long. This is the statistical shadow of your cadence, and it's one of the strongest voice signals there is.
Contraction rate. "Don't" versus "do not," counted per 100 words. Small habit, huge tonal effect — it's the difference between talking and announcing.
Commas per sentence. A proxy for how you build clauses: do you write in clean straight lines, or do you pile on qualifications, asides, digressions?
Vocabulary variety. Unique words in a fixed 200-word window. Some voices circle a small vocabulary deliberately; others range wide.
How to build a good profile
Feed it writing that's genuinely and only yours — old emails, journal entries, posts you wrote before AI assistants existed. 150 words is the minimum; 300–500 makes the numbers steadier. Match the register you'll edit in: if you'll mostly polish professional posts, use professional samples, not texts to your sister. And never build it from AI-assisted writing — you'd be fingerprinting the machine.
What the numbers can't do
Honesty matters here. The profile measures form, not meaning. It can tell you a draft's rhythm is unlike yours; it cannot tell you whether the ideas are yours, whether the argument holds, or whether the piece says anything worth reading. It's a compass, not a judge — when NEO says "unlike your samples," that's an invitation to look, not a verdict to obey.
It's also windowed, not omniscient: five numbers can't capture humor, warmth, or the way you land a paragraph. Two writers could match on all five and still sound nothing alike. The profile narrows the gap between "generic" and "you"; the last mile is still yours to walk.
Privacy, concretely
The profile is computed in your browser and saved in your browser's local storage. It is never uploaded — there is no server to upload it to. Click "forget profile" and it's gone. That's the whole data lifecycle.
Ready to try it? Open the editor, paste your sample in the voice profile panel, and click build. Two minutes, once.