Chrome Extension

Reply fast. Post often. Grow faster.

FastPost AI puts an AI button inside X, paste a few old tweets, we learn your voice, and every reply you generate sounds exactly like you wrote it

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Already have an account? The extension works with your existing FastPost AI login.

For youFollowing

Mohamad@Mohamad_Biomy

I tried to grow on X. I was dedicating to post 3 or 4 posts per day. One post was taking ~25 minutes from me. That was exhausting and frustrating. So I built @FastPostAI.

FastPost AI

GENERATED REPLY

25 min per post is wild. that's exactly why you built @FastPostAI — most people just complain about the problem. you solved it.

Custom Instructions

Regenerate

Insert Reply

From install to first AI reply in 4 steps

Setup takes about 5 minutes. After that, every reply on X takes 10 seconds.

Install the extension

Add FastPost AI to Chrome from the Web Store. It takes one click and needs no special permissions beyond reading X's page content.

Create your account

Train your writing style

Paste 8–15 of your past posts. The AI reads your tone, vocabulary, sentence length, and structure. This takes about 3 minutes and only needs to be done once. After this, every reply sounds like you — not like ChatGPT.

Why training matters: Without a style profile, AI replies are grammatically perfect but generic. With your profile, they match how you actually talk — your sentence length, your punctuation habits, your vocabulary.

Reply to any tweet in your voice

Open X. Find a tweet. Click the 'Reply with FastPost AI' button in the compose toolbar. Your reply appears in seconds — review it, insert it, post it.

Everything the extension does

Instant generation

Click once, get a reply in seconds. The AI uses your style profile and the tweet content to write something you'd actually post.

Your voice, not AI's

The extension uses the same style profile as the web app. Every reply matches your tone, length, and vocabulary — trained from your own posts.

Custom instructions

Set default instructions that apply to every reply — like 'always be contrarian' or 'no emojis'. Or add per-reply instructions directly in the panel.

Before your first reply

Train the AI on your writing style first.

The extension is powerful — but it needs to know how you write. Before you generate your first reply, spend 3 minutes training your style profile.

Here's what to do:

Go to fastpost-ai.vercel.app/dashboard/train
Paste 8–15 posts you've written before
Hit Analyze — the AI builds your profile
Come back to X and generate your first reply

Train my style now

Paste your past posts

Copy 8–15 posts you've already written and paste them in. Any platform works.

AI analyzes your style

FastPost reads your tone, vocabulary, sentence length, and structure.

Generate posts in your voice

Drop an idea, hit generate. Every post sounds like you wrote it.

Start replying smarter on X today.

Free to install. Free plan includes 10 AI replies per month. No credit card required.

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