tldr; Free, open source macOS app and CLI for trusted teams to build with Codex, together: discuss the work, steer one shared local Codex session, review what it changes, and hand hosting between teammates.
multAIplayer lets people build with Codex, together!
multaiplayer is a free, open source macOS app and CLI, built on the Codex app server
In the desktop app, you create a private room around a local project and invite the people you trust. Anyone in that room can chat, share context, and propose the next Codex turn.
Before anything runs, the active host sees:
- who proposed it
- the conversation and attachments being included
- the project association
- model
- sandbox
- any privileged context
The host approves that exact turn, and Codex runs locally on their Mac using their project, tools, and account.
Everyone can follow the assistant response and the intentionally shared activity:
- commands
- file changes
- tools
- web work
- images
- subagents
And it does this all without exposing the host’s credentials or raw local environment.
The desktop app also gives the room a Monaco editor, xterm,js terminals, diffs, GitHub Actions, an in-app browser, the option to use Cloudflare Quick Tunnels to share local development builds with others in the room, and of course, chatting and building with Codex and your trusted team.
So, the conversation, the work, and the review all stay in one place.
Underneath that, multAIplayer connects to the normal Codex app-server running on the host. It isn’t replacing Codex or sending somebody’s project to a remote machine.
Room membership is bound to GitHub identities and verified devices.
Room content is encrypted using (unaudited) RFC 9420 MLS via mls-rs, while the relay handles authentication, authorization, ordering, and delivery of opaque encrypted records. It sees the operational metadata needed to run the service, but the clients handle the room content. multAIplayers offers a free hosted relay, and the option to self-host as well.
And if you would rather stay in the terminal, the CLI is a full client of that same system. You can:
- authenticate
- create or join rooms
- manage secure invites
- chat with teammates
- propose Codex work
- approve turns
- follow activity
- host the local Codex session
All without leaving the terminal.
The CLI is built in Rust and speaks the same relay protocol as the desktop app. It joins the same MLS groups and processes the same encrypted room events.
And because the Codex session belongs to the active host, hosting doesn’t have to get stuck with one person. If they run out of usage, need to step away, or someone else is better equipped for the next part, they can hand hosting to another verified member.
Credentials and running processes don’t teleport. The new host uses their own local project and Codex account, but the room, conversation, and team can keep going!
multAIplayer is open source under Apache 2.0, and welcomes contributions!
You can check out multAIplayer, and download for macOS now through the website or GitHub!