Diagram
← All tools

How to make and share diagrams with Codex app

Codex app (OpenAI’s Codex desktop app) can draw architecture diagrams, flowcharts, and sequence diagrams, but on its own they end up as text in the chat or a file only you can open. Connect Diagram once and every diagram Codex app makes becomes a link you can share, which stays current as the diagram changes.

Set up Codex app, freeHow Diagram works

1. Connect Diagram to Codex app

In the Codex app, open Settings → MCP servers → Add server, choose Streamable HTTP, paste the URL from this snippet, save, and restart. Or add the snippet to ~/.codex/config.toml (%USERPROFILE%\.codex\config.toml on Windows), which the Codex CLI and IDE extension share:

[mcp_servers.diagram]
url = "https://diagram.la/mcp"

Sign in once: After adding it, choose Sign in next to diagram in Settings → MCP servers: sign in with Google and click Allow.

2. Ask for a diagram

Open your repo in the Codex app and start a new task, then describe what you want in plain words. For example:

Codex app draws it, keeps it in your repo’s diagrams/ folder, and gives you a link. You never have to mention Diagram again: it knows to use it.

3. Share the link

Paste it in Slack, a pull request, or a doc. Diagrams start private; add people to the project, share it with your team, or make one public. When it changes, ask Codex app to update it: the link stays the same and every version is kept.

Questions

Is Diagram free to use with Codex app?
Yes. Diagram is free for 5 projects, and there's nothing to install.
Who can see my diagrams?
Only you, until you share. Add people to a project, share it with your team through an org, or make a single diagram public so anyone with the link can open it.
What happens when the diagram changes?
Ask Codex app to update it. The new version lands at the same link, and every earlier version is kept.
Does Codex app need an API key?
No. Codex app signs in to Diagram with your Google account in the browser.

Diagrams in other tools