Synapsdex is a Chrome extension that opens as a side panel inside X (Twitter). It reads the post you're viewing and drafts replies, reposts, posts and hooks. You edit them and post them yourself — nothing is sent automatically.
Each part of Synapsdex exists to help you decide what to write, get a solid AI draft fast, and refine it before you post.
Twelve preset angles. Analytical answers with numbers and base rates; Provocateur argues the strongest opposing case; Storyteller replies with a short anecdote; Punchline writes a single quotable line; Supportive agrees and adds value. You pick one, or the app suggests the most fitting angle based on the post.
Buttons that set the type of output: a Reply, a Repost caption, a standalone Post, a Counter-argument, a sharp Question, a TL;DR of a long thread, a dated Prediction, or Receipts (one verifiable fact or named source). You can hide the ones you don't use or create your own.
Instead of full replies, the Hooks actions generate five distinct opening lines for a post of your own. Useful when you're starting a thread and want a strong first sentence — curiosity gaps, bold statements, surprising facts or relatable openers. Each is scored.
Type a name and the drafts are written in that style. For a public figure, the extension pulls the person's public bio so the wording fits their worldview. A slider controls how much the persona colours the result versus the chosen angle.
Sniper Vision scores reply opportunities on your timeline by how much traffic a post has versus how many replies it already has, so you can prioritise. You set the keywords it watches for, and a list of banned words the AI must never use.
Works two ways. The no-key mode uses X's built-in Grok, so you can start with no setup. Or connect your own API key (OpenAI, Anthropic, xAI) for higher quality and the full learning loop — requests go straight to that provider and your key stays in your browser.
A settings window where you manage every archetype and action, your hooks, personas, filters, the prompt template and your API keys.
Archetypes. Turn each of the twelve angles on or off, rename or edit them, or create your own.
Actions. Choose which buttons appear in the panel — Reply, Repost, Post, Counter, Question, TL;DR, Predict, Receipts — or build your own.
Hooks. Manage the generators that produce five scroll-stopping opening lines for your own posts.
Synapsdex does not connect to the X API and does not automate your account. It reads what is already on your screen and lets you paste a draft into X's composer — the same thing you would do by hand. It never posts, likes or follows on its own.
Your settings and personas are stored in your browser. When you generate, the request goes only to the AI provider you chose, using your own key. There is no Synapsdex server in between.
The extension only drafts. You read each option, edit it if you want, and decide whether to post it. Because every action is taken by you, your account behaves exactly like a careful human using X normally.
Today, Synapsdex is a one-time purchase. When the launch ends, new users will move to a monthly subscription — but everyone who buys the lifetime deal now keeps everything, free, for good.
Add it to Chrome and see how it writes — right inside X.
The price climbs as the launch fills up — $19 today is as low as it gets. Pay once and keep Synapsdex for life; after launch it becomes a monthly subscription for new users, but you'll never pay again.
Once the launch ends, Synapsdex becomes subscription-only — the lifetime price won't come back. Secure payment via Gumroad.
What it is, how it stays safe, and how it compares to other AI reply tools for X (Twitter).
Synapsdex is an AI writing assistant for X (Twitter), built as a Chrome extension. It opens as a side panel, reads the post you're viewing, and drafts replies, reposts, posts and hooks. You review, edit and post everything yourself.
Yes. You can start free with five drafts per day — no account and no card. A one-time lifetime upgrade removes the daily limit and unlocks every archetype and action.
No. Synapsdex never connects to the X API and never posts, likes or follows on its own. It only drafts text; you copy it into X's composer and post it yourself, so your account behaves like a normal human using X.
Synapsdex works on Chrome, Brave and other Chromium-based browsers. You add it from the Chrome Web Store in one click.
No. The no-key mode uses X's built-in Grok, so you can start with zero setup. You can also connect your own OpenAI, Anthropic or xAI key for higher quality — the request goes straight to that provider and your key stays in your browser.
Synapsdex runs entirely in your browser with no server in between, gives you twelve strategic archetypes and nine actions, scores hook options, and never automates your account. You stay in full control of what gets posted.
