Show HN: ReplyFast – Let AI reply to your emails, instantly and in your style

Hey HN,

I built ReplyFast, a tiny AI tool that does one thing only: It replies to your emails instantly – in your own tone – with 1 click.

No chat interface, no fluff, no distraction. Just paste the incoming message, hit “Reply”, and get a clean, human-sounding response ready to send. Think of it as “muscle memory for email replies.”

Why I built it: I was wasting too much time replying to basic emails or DMs. Most existing tools either sound robotic, take too many steps, or try to do too much. I just wanted something that feels like me, but faster.

Tech: – Next.js + GPT-4 – Hosted on Vercel – Just one page + a dashboard – Tone selector, instant suggestions, no login required to try it

Pricing: – Free to test – Paid plan for frequent users (still finalizing based on feedback)

Would love your thoughts on: – What features would you want for email productivity? – Would you pay for this if it saves you hours weekly? – Anything that feels off or unnecessary?

You can check it here :https://www.replyfast.net/

Thanks – Viggo