Riff is a free Chrome extension that drafts posts, replies and DMs for X, LinkedIn, Facebook and Instagram right in your browser. It runs on-device with Chrome’s built-in Gemini Nano, so your text never leaves your computer. There is no account to create, no API key to buy and no monthly bill.

How it works
You open a post, paste your rough point, and Riff writes a fresh reply for that exact post. Gemini Nano, the AI built into Chrome, does the writing on your own machine. You read the draft, edit it if you want, and press send yourself. Riff fills the reply, comment, message or post box and stops there. It never presses Reply, Comment, Post or Send for you, and it does not schedule anything.

Replies, DMs and posts
Riff writes replies for posts on X, LinkedIn, Facebook and Instagram. It also answers DMs in LinkedIn Messaging, Messenger on facebook.com and Instagram Direct. When a chat is new, it can write the first message. You can draft your own posts too: drop in rough notes, ask for changes in plain words, and pick a hook you like.

Your voice, your settings
You decide how the reply sounds. Simple dials control how smart, how salesy and how bold a reply should be, along with tone and length. Tell Riff once who you are and how you write, and it follows that voice. You can keep separate voices for brands you run, so you can post as yourself or as your company. Each draft is checked against your recent replies so it does not repeat itself.

Private by design
Everything runs on your computer. There are no Riff servers and no account. Your settings, notes, drafts and history stay in Chrome storage on your machine. Because the model is built into Chrome, nothing you write is sent to an outside AI service.

Who it is for
Riff suits anyone who replies a lot on social sites: founders, marketers, creators and professionals who want to reply to posts in their field without starting from a blank box, leave real comments on LinkedIn instead of a bare “Great post”, answer DMs faster, or turn rough notes into a LinkedIn post, an X thread or an Instagram caption.

What you need
Riff needs desktop Chrome 138 or newer on Windows 10 or 11, macOS 13 or later, Linux or a Chromebook Plus. You also need about 22 GB of free disk space for the one-time model download, and a GPU with more than 4 GB of video memory, or 16 GB of RAM and 4 or more CPU cores.

About the maker
Riff is built by Michael Zima, Founder of Zima Media OÜ in Tallinn, Estonia. He replies a lot on X and LinkedIn and wanted a reply tool with no account, no API key and no monthly bill, so he built Riff on the AI inside Chrome. Riff is bootstrapped and in an early stage. Install it from the Chrome Web Store: https://chromewebstore.google.com/detail/riff-fresh-replies-for-x/oapafjkedoiikjneaadcdojmophehfhl