The console

Firenook has its own web console. It shows every emulator the suite runs, live, and lets you browse and change their data, call your functions, read the log and test your Security Rules. It replaces Google’s Emulator UI, on the same port.

Open it

With the default ports, the console is at:

http://127.0.0.1:4000/console

In the terminal Firenook draws, press o to open it in your browser. The address is also the first row of the ready summary, so you can click it there. The port is the Emulator UI’s: emulators.ui.port in firebase.json changes it, and the root of the port, http://127.0.0.1:4000/, sends the browser to the console. With the default host, localhost, the console listens on both 127.0.0.1 and ::1, so http://localhost:4000/console works whichever address your browser tries.

The console is on by default with emulators:start. emulators.ui.enabled: false in firebase.json turns it off, together with the logging listener, as in the official suite. emulators:exec leaves it off unless you pass --ui or firebase.json sets emulators.ui.enabled: true. --ui turns the console on even when firebase.json turns it off, as the official --ui does.

Sections

The sidebar groups the sections by what they do: Data, Compute, Messaging and Observe. A section whose emulator is not running is dimmed. Open it and it says why, for example that firebase.json does not configure the service or that --only left it out, and shows the change that turns it on.

Section	Pages	What you do there
Overview	one	See whether every emulator is healthy, what each holds and the newest problems; take a snapshot of the data or reset it; read the engine’s version and configuration
Firestore	Data, Rules	Browse collections and documents in a grid, edit them, run a query the way your app does, and view the data as a given user would. The Rules page edits the rules and shows every decision with the line and the values behind it, with a playground and saved tests
Authentication	Users, Inbox, Activity, Settings	Search and edit users and their custom claims (with the token the claims produce); read every email link and SMS code the emulator would have sent; see every Auth call with its exact error; manage tenants and blocking functions
Storage	Files, Rules	Browse every bucket and folder with live counts and sizes, preview images, video, audio, PDFs and text, edit metadata and download tokens, upload files and folders, and move, copy or delete at any scale. The Rules page works as Firestore’s does
Functions	All functions, Invocations	See every function by codebase with its trigger and health, call HTTP and callable functions as any user, send test events, and read every invocation with its logs and timing, or run it again
Extensions	one	See each instance with its source, whether it can start offline, its parameters and where each value comes from, the functions it adds and the events it emits; reconfigure and reload it
Pub/Sub	Topics, Schemas	See topics with their subscriptions and the functions they trigger, every message and who received it, publish JSON, text or bytes with attributes, read or purge a backlog, and check Avro schemas as you type
Eventarc	Events	See every event on every channel with the triggers it reached or missed, and publish a custom event
Cloud Tasks	one	See queues with their settings and counters, waiting and running tasks with their attempts and next retry, and finished ones; enqueue by hand, run a task now, pause, hold and purge
Logs	one	Read every emulator’s log in one stream with filters and counts, structured payloads, and each function invocation as a group, with links into the section a line is about

Sections link to each other wherever one names what another shows: an invocation opens its log lines, a log line opens the section it is about, and a denied request opens its decision on the Rules page.

The Rules pages

The Firestore and Storage Rules pages show the rules in force for the database or bucket you choose. For a Firestore database that firebase.json does not list, the page says whose rules govern it: the (default) entry’s, or the first entry’s, as the official emulator applies its one rules file to every database. Applying rules on the page gives that database its own.

Saved tests on the Firestore Rules page download as one firestore.rules.test.ts file for @firebase/rules-unit-testing and Vitest, one test per saved case, which runs against Firenook in your tests or in CI:

npx firenook emulators:exec --only firestore "npx vitest run"

The console follows the engine live, so lists, counts and badges change as your app works. A browser keeps one connection for all its console tabs. When the connection drops, the top bar says so once; when the engine restarts, the console says so and loads the data again.

The Overview’s data card

The Overview’s data card works on the whole suite:

• Snapshot downloads the data as a zip of a standard export, the same format --import reads, or saves it on the machine the engine runs on.
• Reset deletes one section’s data, or all of it. Resetting more than one section asks for the project id. A Firestore reset runs no Functions triggers unless you ask it to.

Each runs as a job: one at a time, with its progress shown in every open tab, and it carries on if you close the tab that started it.

Find your way

Key	Does
⌘K or Ctrl+K	Search the console: users, collections, documents, files, functions and actions
?	Show every keyboard shortcut, including the current page’s
[	Collapse or expand the sidebar
t	Hide or show the current section’s panel

Light and dark

The three buttons at the end of the top bar pick light, dark, or the operating system’s setting. The choice is kept per browser. On the system setting, the console changes when your system does.

Connect your app

The Connect button, in the top bar on every page, opens a dialog with the code that points an app at this engine, with the ports in use, the project id and the host your app sees:

Group	Tabs
Apps	Web, Flutter, Apple, Android
Servers	Admin (Node), Python, Go, Java
Configuration	Environment variables, firebase.json
Agents	Coding agent

For a demo- project the app snippets are complete and run as printed; for a real project id they keep your app’s own configuration and add the lines that point each SDK at the emulators. Each snippet sets what its SDK reads, since a service whose setting is missing goes to production:

• Apple turns TLS off for Firestore (settings.isSSLEnabled = false), which the emulator does not speak; useEmulator alone leaves it on.
• Admin (Node) sets the variables for Firestore, Auth, Storage, Pub/Sub, Cloud Tasks and Eventarc.
• Python sets STORAGE_EMULATOR_HOST, a URL, because Python’s Storage client ignores FIREBASE_STORAGE_EMULATOR_HOST, and Cloud Tasks’ variable. It sets none for Eventarc, which the Python SDK does not publish to.
• Java builds its Storage and Pub/Sub clients on the emulators, since they read no variable. It has nothing for Cloud Tasks or Eventarc.
• Python, Go and Java point the SDK at demo credentials, the file emulators:exec writes, so it never asks Google for a token.

The Environment variables tab lists every variable emulators:exec sets for the services that run. The host picker offers the engine’s own address, the address you opened the console at, 10.0.2.2 for the Android emulator, or one you type, and remembers your choice. The firebase.json tab prints the emulators block for the ports this engine runs on. The Coding agent tab sets up the MCP server and shows when an agent last called it.

A link can open the dialog on one tab: /console?connect=python.

Offline

The console is part of the engine binary. Its pages, scripts and fonts come from the engine itself, so it works with no network connection.

Old Emulator UI links

Google’s Emulator UI is not served since 0.2.0-next.3. Its old addresses, in bookmarks or in links other tools print, lead to the console’s matching section:

Old address	Leads to
/	/console
/firestore/...	/console/firestore
/firestore/requests	/console/firestore/rules
/auth	/console/auth
/storage/...	/console/storage
/functions	/console/functions
/extensions	/console/extensions
/logs?q=...	/console/logs?q=..., with the query kept

A path inside a section, such as one document’s, opens the section’s first page rather than that document. /api/config on the same port still answers with every emulator’s host and port, for the tools that read it.

Reach it by another name

The console answers only for the names that can only mean this machine: localhost, 127.0.0.1, ::1, the --host address, and every name under localhost, such as demo-shop.localhost. Browsers resolve those names to your own machine themselves, so no web page can point them elsewhere. That keeps other sites you visit from reaching the console, which can change and delete everything the emulators hold.

Reached by any other name, through a reverse proxy, a tunnel, a container’s service name or a cloud host, it refuses the request:

$ curl -H 'Host: emulator.internal:4000' http://127.0.0.1:4000/console
{"error":{"code":"permission-denied","fix":"Start the engine with --allowed-hosts emulator.internal if you meant to.","message":"This console does not answer for host emulator.internal."}}

Name the hosts it should answer for with --allowed-hosts, comma-separated:

npx firenook emulators:start --allowed-hosts emulator.internal,dev.example.test

Started with --host 0.0.0.0 (or ::) and no --allowed-hosts, the console answers any name, and Firenook warns that the emulators are reachable, without authentication, from any device that can reach your machine. With --allowed-hosts as well, it answers only those names and the loopback ones.

Local proxies that name apps under .localhost, such as portless, need no flag. Point the name at the UI port, since that is where the console listens:

portless alias demo-shop-console 4000

Then open https://demo-shop-console.localhost/console, with :1355 after the name when the proxy runs without sudo. The Connect dialog’s snippets keep 127.0.0.1, because the name leads to the console, not to the emulators’ own ports.

Next

The terminal covers the screen Firenook draws while it runs, and Ports lists every listener. The console page shows each section in pictures.