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Fireemu

Emulator UI

fireemu up serves the Emulator UI at http://127.0.0.1:4000/ui/.

Terminal window
# Another port
npx fireemu up --ui-port 4001


# No UI
npx fireemu up --ui-port 0


# exec starts no UI unless asked
npx fireemu exec --ui -- npm test

If the default port is busy, up starts without the UI; check the startup output.

What it shows

Section titled “What it shows”
  • Overview: the project, version, virtual clock (frozen, or following real time) and running services, and the Host names the emulators answer: the built-in names, the entries you added with network.allowedHosts and whether single-label names are allowed.
  • Authentication, Firestore and Storage: browse and manage users, documents and objects.
  • Functions: registered functions with the runtime of each (Node.js or Python, and the runtime your firebase.json declares), their triggers, invocation results and logs, and the runtime status: work pending, running, waiting for a retry or dead-lettered, Auth events held while the event queue is full, tasks in flight, the state of each codebase’s runner, and the exports the runner found and could not serve. Run a scheduled function immediately, or advance the clock to its next occurrence.
  • Hosting: the site Fireemu serves, its local URL, the public directory (with a warning when it did not exist at start), and the rewrites, redirects and headers in the order they apply. The page reads your firebase.json; it does not record requests.
  • Realtime Database: browse the data at a path, replace, patch or delete it as the local administrator, read and replace the instance’s Rules, and run an anonymous request to see how the Rules answer it.
  • Alerts: publish Firebase alerts to functions that listen for them.
  • Rules: the newest 100 traced Firestore Security Rules decisions, with bounded expression results. Tracing starts with the UI or the first control-API read; a new ruleset clears the history. See Security Rules for diagnostic limits.
  • App Check: registered apps and debug tokens.
  • Runtime: the virtual clock. Move it forward, or backwards with Allow moving backwards.