Open Mercury

Group chat, without the noise.

Hubs, channels and DMs that stay calm until you touch them. Served from one Node file and one HTML file.

Open Mercury Download for Mac Download for Windows Get the desktop app

Desktop apps for Mac and Windows

Mercury in a browser tab. The Mac and Windows apps are the same app in its own window.

The essentials, done quietly.

Everything a group needs to talk every day. Still at rest, liquid when you touch it, in light or dark.

Hubs and channels

Give each group its own hub and split the talk into channels, with unread dots and mention counts that show where to look.

Direct messages

Pick anyone in the member list and press Message. Only the two of you can read the conversation.

Replies, edits, reactions

Reply to one message, fix your last one with the up arrow, or react instead of adding another line.

Files, GIFs and links

Drop in any file up to 60 MB, from a zip to a video. Search Giphy or Tenor, or paste a link to see its preview inline.

Presence and status

See who is online, idle or busy, who is typing right now, and a short bio on every profile.

Ctrl K to jump anywhere

Press Ctrl K, or Cmd K on a Mac, type a few letters and land in any channel, hub or conversation.

Mercury for Mac and Windows

The same app in its own window, with system notifications and an unread badge. Connect to any Mercury server, or host one for friends on your Wi-Fi.

The apps are not signed yet, so the first launch asks once: choose Open Anyway on a Mac, or More info, then Run anyway on Windows.

Host your own in a minute.

Zero npm dependencies and nothing to build. Any machine with Node 18 runs it, and on Replit it takes one import and one press of Run.

  1. 1

    Import it on Replit

    Create a Repl from the GitHub repository, or upload the folder as a zip.

  2. 2

    Press Run

    Nothing installs. The server starts on port 3000 and keeps its data in one JSON file.

  3. 3

    Share the link

    The site lives at / and the app at /app. Everyone who opens it joins the same hubs, live.

Or on any machine with Node 18 or newer

$ npm start

> mercury-chat@1.4.0 start
> node server.js

Mercury is live on http://localhost:3000

GIF search is optional: add GIPHY_API_KEY or TENOR_API_KEY. Pasted GIF links preview either way.