Show HN: ReplyFast – Instantly reply to emails in your own tone (1-click)

1 skyzouw 0 8/3/2025, 9:47:46 AM

Hey HN,

I built ReplyFast, a minimal AI tool that helps you reply to emails instantly – in your own style – with just 1 click.

You paste the incoming message, pick a tone (friendly, direct, confident, etc.), and ReplyFast writes a clean, human-sounding reply you can send immediately. It’s like having a muscle memory for email responses, powered by GPT-4.

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Why I built it: I was wasting way too much time replying to emails and DMs that didn’t need 100% of my brainpower. Most tools either feel clunky, overkill, or too robotic. I just wanted something that: • Sounds like me • Works in 3 seconds • Doesn’t turn into another inbox or SaaS dashboard

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Tech: • Next.js (App Router) • GPT-4 • Hosted on Vercel • Fully client-side preview, no login needed to try it

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What I’m looking for: • Is the output natural enough? • What would make you use this every day? • Would you want Gmail/Twitter/LinkedIn integrations? • Would you pay to save hours per week on emails?

Try it → https://www.replyfast.net/ Happy to answer anything or take roast-level feedback!

– Viggo

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Show HN: ReplyFast – Instantly reply to emails in your own tone (1-click)

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