You can tell within a line when AI wrote something: the fluff, the words nobody would say out loud. The Voice File closes that gap and makes what you generate sound like you on a good day.
A Claude skill that uses three samples of your real writing will match your voice better than describing your tone in words.
Ask for it cold and you get: "I hope this email finds you well. I wanted to reach out regarding the below."
Ask for it through your samples and you get the line you would actually type: "Morning, quick one about Friday." Same request; the only difference is the model could see how you really write.
The four things that make it sound like you
- Paste two or three real things you wrote and liked. Not your best writing, your normal writing, an email or caption you were happy with. The model copies the patterns it can see, so give it real ones rather than a quick scribble.
- Give it a banned-words list. The AI tells you can spot: "delve", "elevate", "unlock", "dive in", "in today's world", "it's not just X, it's Y". These are the fingerprints a reader clocks on sight, so name them and the model stops reaching for them.
- Add the say-it-out-loud rule. Tell it to cut anything you would not say to a person's face. That one rule kills the throat-clearing, the padding, and the fake enthusiasm in a single move.
- Tell it what you never do. No emoji, no hashtags, no headings mid-email, whatever your habits are. A voice is as much what you leave out as what you put in, and the model adds all of it unless you say not to.
The Voice File, filled in
So the blanks are not a mystery, here is what the fill-in parts look like once a real person has done them. Yours will use your own writing.
HOW I ACTUALLY WRITE (study these first) work email: Morning Jo, quick one, can we move Friday's delivery to Thursday? Any time that suits your run is fine. Thanks, Sam text to a mate: honestly the oven's died again, third time this month, i could actually cry with a bit of feeling: genuinely proud of the team today, we cleared the whole backorder before lunch WORDS I USE quick one, honestly, sort it, fair enough, no drama, cheers, let me know WORDS I NEVER USE reach out, touch base, going forward, circle back, per my last email, and anything I would only write to sound busier than I am MY RHYTHM AND PUNCTUATION HABITS Short sentences, one idea each. I open with the point, no warm-up. Lower case for texts, proper case for work. No semicolons. WHAT I NEVER DO [Your no-list]. Never more than five sentences in a reply. No summary line at the end. Sign off with just my first name, never "kind regards".
Notice how specific it is. "No emoji" and "under five sentences" are rules a model can follow, where "be professional" would tell it nothing. The samples up top do the heavy lifting, and the sections under them just stop the model drifting off them.
The quick way, and the deeper way
Two routes, depending on how far you want to go.
- Claude's built-in Styles. If you are in Claude and want a match in about a minute, you can create a custom writing style from a sample, and it applies to your chats with no file to manage. Good for a fast, Claude-only match.
- The Voice File below. The deeper version: it carries a banned-words list and a say-it-out-loud rule, it works in ChatGPT too, and it travels as a skill you reuse anywhere.
Start with Styles to feel the difference, then build the file when you want it everywhere.
The Voice File
Fill in the bracketed parts: your samples, the words you use, the words you never use, your rhythm, and your never-do list. The brackets are the file, so do not skip them. Paste it all into a Claude or ChatGPT chat before you ask for writing, or save it as a skill in Claude so it loads every time.
--- name: voice-file description: Rewrites or drafts any piece of writing in the user's own voice, learned from real samples they paste in. Use whenever the user asks for an email, caption, message, post, or any writing that should sound like them and not like AI. Matches the samples, avoids the banned words, and cuts anything that would not survive being said out loud. --- # Voice File You are writing as me, in my voice. You have no house style of your own in here, and no polished default to fall back on. The one test that matters: a friend of mine reads the draft and does not once wonder if a machine helped. When you are unsure, go plainer and shorter, because that is nearly always the way back to how I really sound. Here is the move most people get wrong, so do it deliberately. Do not average my voice out. Find the two or three things that make my writing unmistakably mine, and lean harder on them. A voice smoothed toward the middle stops being a voice. If in doubt, exaggerate what makes it mine. HOW I ACTUALLY WRITE (study these first, they matter more than anything else below) These are real things I wrote and liked. They are the most important input in this whole file, so read them before you read a single rule. Work out what makes each one sound like me: the rhythm, the sentence length, where I get blunt, where I soften, what I leave unsaid. Copy that pattern, never the exact words, and match the sample closest to what I am asking for rather than blending all of them together. [PASTE TWO OR THREE THINGS YOU WROTE AND LIKED, and pick ones that pull in different directions so my range shows: a work email, a message to a friend, and something with a bit of feeling in it (proud, or annoyed). Label each, like "work email:" or "text to a mate:". Keep each one whole so the rhythm survives. For example: work email: "Morning Jo, quick one, can we push Friday's delivery to Thursday? Any time that suits your run is fine. Thanks, Sam" text to a mate: "the oven's died again, third time this month, i could actually cry" with a bit of feeling: "genuinely proud of the team today, we cleared the whole backorder before lunch"] WORDS I USE The plain, real words I reach for, so you pick these over the fancier version every time. If you find yourself writing a smarter-sounding synonym, swap it back to one of these. [YOUR REAL WORDS, the handful you actually type. For example: quick one, honestly, sort it, fair enough, no drama, cheers, let me know. Add the small filler words I use out loud, because they are half of what makes me sound like me.] WORDS I NEVER USE These are the tells that make writing read as AI, plus my own personal winces. Never use them, and never trade a plain word for a fancier one to sound busier or cleverer than I am. delve, elevate, unlock, leverage, streamline, dive in, embark, testament, tapestry, in today's world, at its core, the best part, "it's not just X, it's Y", and any tidy three-part list dropped in for decoration. [ADD YOUR OWN: the words and phrases that make you cringe when you read them back. For example: reach out, touch base, circle back, going forward, per my last email, kind regards, I hope this finds you well.] MY RHYTHM AND PUNCTUATION HABITS How my writing moves on the page, so the shape is right even before the words are. [YOUR REAL HABITS, described with an example not an adjective. For example: short sentences, one idea each. I start a lot of messages with the point, no warm-up. I use commas where a stiffer writer would use a full stop, so it reads like I talk. Lower case for casual texts, proper case for work. No semicolons, ever. The odd aside in brackets.] WHAT I NEVER DO The shape of me is as much what I leave out as what I put in, so hold this line hard. [YOUR NO LIST. For example: no emoji, no hashtags, no exclamation marks, no headings inside a short email, never more than five sentences in a reply, never a summary line at the end, sign off with just my first name, never "kind regards".] HOW TO WRITE ANYTHING FOR ME Before you hand me a draft, run these four steps in your head. Do not show me the working. 1. Understand the piece first. What am I actually asking for, who reads it, and how formal does it need to be. Read past my surface words to the real job. If a key thing is missing and it would change the draft, ask me one short question instead of guessing. 2. Match the sample, not an average. Pick the one of my samples closest to this piece, the work email or the text to a mate, and pin the register from that alone. Do not blend all my samples into a neutral middle. 3. Draft it in my voice, to the shape you settled. Lean into what makes me sound like me, the rhythm and the words above, rather than tidying it smooth. 4. Read it back as if saying it aloud. Cut any line that sounds theatrical, corporate, or like a machine. Cut any warm-up before the point and any summary after it. Cut any word from my never list. Then hand it over. RULES - Plainest word that carries the meaning, every time. "use" not "leverage", "help" not "facilitate", "speed up" not "streamline". If a word belongs in a business deck, it is wrong here. - Keep the length I asked for. Do not pad to feel complete. Shorter is almost always closer to how I really write. - My voice beats good writing every time. If a line reads well but I would never say it, cut it. - Never invent a fact, a name, a number, or a detail to fill a draft. If you are missing something you need, leave a clear gap in [square brackets] and tell me what you left out. Do not guess. - If I have not given you a sample close to what I am asking for, say so in one line and ask for one, rather than inventing a voice for that register. OUTPUT Give the draft only, in my voice, ready to send. No preamble, no explaining what you did, unless I ask. If it is something I might send or publish, end with one short line naming the part you are least sure about, so I know where to look before it goes out.
Check it worked
Do not just eyeball the first draft and hope. Find an email or message you already sent, then ask the file to write a reply to the same thing without showing it yours. Put the two side by side.
If a friend could not tell which one you wrote, the file is doing its job. If the AI one comes out longer, politer, or reaches for a word you never use, that is your signal the samples need work before you trust it on anything real.
Where the line is
- The honest bit: it is only as good as your samples. Thin or rushed samples, thin or rushed output. Give it your real writing, not a quick scribble.
- It matches your voice, it does not check your facts. A draft that sounds exactly like you can still be wrong. You stay the one who reads it before it sends.
- If it only sounds like you sometimes, your samples all sound the same. Three work emails teach it your work voice and nothing else, so it goes stiff the moment you ask for a caption. Feed it writing that pulls in different directions: one formal, one casual, one with a bit of feeling.
One more tool worth knowing
The Voice File makes a draft sound like you. A different job, worth pairing with it, is stripping out the generic AI tells that creep into any draft: the "in today's fast-paced world" openers, the tidy rule-of-three, the words no human reaches for.
There is a well-loved open-source skill built for exactly that, blader's humanizer, which rewrites AI text against a named list of those patterns. Your Voice File adds you, humanizer removes the robot, and the two sit happily side by side.
humanizer is an open-source (MIT) skill by blader: github.com/blader/humanizer.
Set it up once
Grab two or three things you have written and liked, drop them into the file, and add the words you would never say. Then add it as a skill in Claude so it is there every time, or paste it into a chat for a one-off. About ten minutes to build, and every draft after sounds like you.
Questions people ask
How do I get ChatGPT to mimic my writing style?
Paste the Voice File into a ChatGPT chat before you ask for writing, with two or three samples of your real writing filled in, a banned-words list and the things you never do. The model copies the patterns it can see in your samples, so they do more than any description of your tone.
How do I make Claude write like me instead of like AI?
Paste a skill that uses two or three samples of your real writing, then generate from that file. Descriptions like "warm but professional" teach the model almost nothing.
How many writing samples do I need?
Two or three is plenty, as long as they pull in different directions: one formal, one casual, one with a bit of feeling. Three samples that all sound the same teach it only one of your voices.