Show HN: PostIdentity, an AI that writes in your voice

5 points by mutiny1907 17 hours ago

I built PostIdentity because I was tired of rewriting the same idea for different platforms in different tones. On X I needed something short and casual. On LinkedIn it had to be longer and more formal. I spent more time polishing tone than writing.

PostIdentity is a web app that learns how you write and builds AI identities that capture more than just tone. Each identity encodes pacing, intent, and personality to create posts that sound like you or match different styles for brands or clients.

Unlike ChatGPT or other AI writing tools, PostIdentity keeps each identity persistent instead of recreating it from a prompt each time. It remembers how you write, the tone you use, and the style of your previous posts, so your output stays consistent. You can also take one idea and generate several versions of it across different identities, for example one for X and another for LinkedIn.

You can: - Create multiple identities for different voices or projects - Generate posts instantly using any identity - Refine results to adjust tone or length - Use the Chrome extension to write directly on X and LinkedIn

Signup is required, but you get an instant demo and 5 free posts when you log in.

Demo video (1 min): https://www.youtube.com/watch?v=C9GeT0b4XFE

Built with React, TypeScript. Uses Supabase, Claude Haiku 4.5 and GPT-5.

I’m building this as a side project alongside my full-time job, but I’m putting a lot of hours into it each week. I have plenty of exciting ideas to expand it further and would love to hear what you think could make it more useful, and if you would use this yourself.

Happy to answer any questions or share more details if you’re curious.