Free tool

Voice Prompt Generator. Measured from your real writing.

Paste 3-5 pieces you actually wrote. The tool measures how you write — sentence length, contractions, punctuation habits, openers — and builds a five-section voice prompt for Claude or ChatGPT.

Runs in your browser. Nothing you paste is uploaded, stored or logged.

STEP 1

Paste your writing samples

3-5 real pieces, 400+ words combined. LinkedIn posts, client emails, newsletter issues — anything that genuinely sounds like you. Separate pieces with a blank line. Don't paste AI-assisted drafts; the tool would measure the AI's voice, not yours.

STEP 2

A few details


                

            

        

    


    

        

            
What to do with it

            
Three steps from prompt to on-voice content

            
    
                
  1. Load it. Claude: paste it into a Project's custom instructions (full Claude walkthrough). ChatGPT: paste it into a custom GPT's instructions (full ChatGPT walkthrough).
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  2. Test it. Ask for 10 hooks, one full post and one rewrite of a generic paragraph. Read each output and ask: would I actually write this? Tighten the rules that failed.
    3. 
                
  3. Go deeper. This is a measured starter prompt. The hand-built version — voice essence written from interview questions, tone calibrated per platform, signature moves named from your best posts — is the difference between 70% and 90% voice match. The complete voice prompt guide covers the full build, or the free Voice System Playbook walks it step by step.
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Want the whole system built for you?

                
The Voice Build ships a hand-calibrated voice prompt, a custom GPT trained on your voice, 65 ready-to-publish pieces and 30 supporting assets. Built from your existing writing in 7 working days.

                See The Voice Build
            

        

    


    

        

            
Questions

            
Frequently asked questions

            
Is my writing uploaded anywhere?

            
No. The analysis runs entirely in your browser. Nothing you paste is sent to a server, stored or logged. You can disconnect from the internet after the page loads and the tool still works.

            
What is a voice prompt?

            
A 500-800 word document that tells an AI tool how you write: sentence length, banned words, tone rules, signature moves. Loaded into Claude or ChatGPT, it makes the output sound like you instead of the model's default voice. Full definition here.

            
How accurate is the generated prompt?

            
The mechanical rules are measured directly from your samples, so they're as accurate as the writing you paste. Expect a solid starter. A hand-built prompt still wins on nuance — that's a 4-6 hour job with the five-section method, or a done-for-you build.

            
How many samples do I need?

            
3-5 pieces, 400+ words combined. The more representative, the better the prompt. Real posts beat polished bios.

            
Where do I paste the finished prompt?

            
Claude Projects custom instructions, a ChatGPT custom GPT, or any tool that accepts system instructions. Voice prompts are plain text and tool-agnostic.