Riff is a free Chrome extension that helps you reply and post on social media without staring at a blank box. It drafts posts, replies and direct messages for X, LinkedIn, Facebook and Instagram in your context — you review, edit and send; nothing is posted automatically, and you stay the author of everything that goes out. What makes Riff unusual is where the AI runs.
It uses Gemini Nano, the model built into Chrome, so drafting happens entirely on your own device. There is no account to create, no server round-trip and no subscription: your text is never sent to the developer’s servers because there effectively aren’t any involved in the writing process. That makes it one of the few AI writing helpers that is private by architecture rather than by policy promise, and completely free to use. Setup is minimal — install the extension, open one of the supported networks, and ask Riff for a draft when the cursor blinks at you. A note on the name: this Riff (riffreply.com) is an independent extension and is not affiliated with riff.ai, the AI app-building platform also listed on Tooloso.