You have a point to make in response to a post, but the blank reply box turns it into a small writing assignment. You could type the same kind of opening again, or spend time making a short comment sound like you. Riff is a Chrome extension aimed at that moment: give it a rough point, and it drafts a reply in the context of the post or conversation.
That makes it a drafting aid for social activity, not a tool for publishing on your behalf. Its maker says it uses Gemini Nano, the AI built into Chrome, and keeps the work on your computer. You still review the text and decide whether to send it.
The problem is the blank box, not the idea
Riff is for people who already know roughly what they want to say but do not want to compose every reply from scratch. The distinction matters. It is not presented as a service that invents your opinion or manages your social presence. You supply the substance, even if it is just an unfinished note, and Riff turns it into a response shaped for the post in front of you.
The workflow begins on X, LinkedIn, Facebook or Instagram. From the Chrome side panel, you can use the control beside a reply or comment box, or work from a chat or post field. Riff reads the relevant post and context, or the conversation in a DM, according to the product description. You paste your point, then choose how direct, sales-focused or adventurous the draft should sound.
This is useful when the hard part is getting from a thought to a readable first version. It is less useful if you want a tool to decide what your position should be, or to generate a stream of replies without your input.
A draft goes into the box, not out to the audience
After generating a reply, Riff can revise it with plain-language instructions or preset changes such as shortening it or softening the pitch. The draft is inserted into the site's reply field, where you can edit it. You press send yourself. That last step is not a footnote: Riff does not publish or send messages for you, so it cannot take over the final judgment or the work of handling a conversation.
The same basic approach extends to direct messages. Riff can draft replies in LinkedIn Messaging, Messenger on Facebook and Instagram Direct. For a new chat, it can draft an opening message. The developer says you can leave your own point blank for a DM reply, letting the message history provide the starting context. For posts of your own, you can provide rough notes, ask for changes, and choose among alternate opening hooks. The page also describes adapting a draft for another supported platform, such as reshaping a LinkedIn post for X or Instagram.
So the product covers more than comments, but the common thread is still drafting in the active browser context. It is not a general-purpose writing workspace detached from social sites.
Local processing comes with a browser constraint
The developer says Riff runs on the computer using Chrome's built-in Gemini Nano, with no account, API key or server involved. That may appeal to people who do not want to send draft material to a separate writing service. These are the developer's privacy and architecture claims, rather than independently verified guarantees. The product depends on Chrome and the browser's built-in AI, so it is not a fit for someone looking for a browser-independent writing app.
Riff is free. Its focused platform support is another practical boundary: the listed destinations are X, LinkedIn, Facebook and Instagram. If your work happens elsewhere, this description gives no reason to expect Riff to help there. And because it only inserts a draft for you to review, it does not solve the broader job of planning a publishing calendar, managing replies, or deciding which conversations deserve attention.
Riff makes sense for someone who regularly writes on the supported social platforms and wants help turning their own rough thoughts into usable replies, DMs or posts without giving up the send button. It is a poor fit for people who want automated engagement, a full social media management system, or a writing tool that works outside Chrome.
Fresh replies for every post, written on your computer