Keep your firebase.json, SDKs and ports, and change one word in your script. No Java to install, and your data survives restarts.
npm install --save-dev firenookSame flags, same ports, same export format. Your project stays as it is, and firebase-tools stays for deploying.
- "emulators": "firebase emulators:start --import ./data"+ "emulators": "firenook emulators:start --import ./data"
Read the way the Firebase CLI reads them.
Your code and config stay as they are.
connectFirestoreEmulator, FIRESTORE_EMULATOR_HOST and the rest connect unchanged.
Imports and exports the official format, both ways.
Your SDKs connect to them as they connect to Google’s: the same hosts, the same ports, the same environment variables.
Native and web SDKs, realtime listeners, Security Rules, named databases, and the official import and export.
Every operation of the official Auth emulator: password, email link, phone, MFA, passkeys, tenants and blocking functions.
The Firebase and Cloud Storage APIs, with Security Rules evaluated natively, firestore.get() included.
HTTP, callable and streaming functions, and every trigger: Firestore, Storage, Auth, Pub/Sub, Eventarc, schedules and task queues. Code reloads on save.
| Time | Function | Trigger | Summary | Status | Duration |
|---|---|---|---|---|---|
| 13:06:19 | stripeWebhook | http | POST / | 500 | 1.1 ms |
| 13:06:18 | sendReceipt | firestore | orders/mzbnHY1n79leG5ioi2nD created | 200 | 1.8 ms |
| 13:06:18 | checkout | http | POST / | 201 | 6.3 ms |
| 13:06:18 | sendReceipt | firestore | orders/c0yT9Jkt9NGpiX7HMV9r created | 200 | 1.7 ms |
| 13:06:18 | checkout | http | POST / | 201 | 5.0 ms |
Every RPC over gRPC and HTTP/JSON: push, ordering, filters, dead-letter topics, seek, snapshots and schemas.
nightlyReport, every day 02:00: next run 2026-10-24 02:00 UTCQueues for onTaskDispatched, with the official retry and rate-limit behaviour.
Custom events delivered to onCustomEventPublished, and the Firebase services’ own.
Extensions from local, vendored or registry sources, offline once vendored.
The orders, users, files and calls above are from a run of the demo project, as Firenook returned them. Realtime Database, Hosting, App Hosting and Data Connect are not emulated; a firebase.json that configures them still starts, with a warning. What each service covers.
Two hours of a production app’s traffic against each emulator in turn, every operation timed by the client.
10× less
40× faster
19× faster
52× sooner
8× faster
61% less
The app holds 211,205 Firestore documents and 6.7 GB in Storage; both emulators ran on one server. Firenook answered 25 of 26 query shapes faster and tied on the last. How it was measured.
Add --keep-data and Firestore, Auth and Storage come back with all your data in about half a second, even with millions of documents. No export at every stop, no import at every start.
A crash loses at most the last second of writes, where the official emulator loses everything since its last export. A stop always closes the data cleanly.
npx firenook emulators:start --keep-dataOfficial emulator
Stop: export, 50–57 sStart: import, 21.6–23.6 s
Firenook
Stop, 0.04–0.30 sStart, 0.54–0.57 s
$ npx firenook emulators:exec "node --test checkout.test.mjs" firenook: Starting emulators: auth, functions, firestore, pubsub, storagefirenook functions: Loaded functions definitions from source: checkout, sendReceipt, stripeWebhook, nightlyReport.All emulators ready✔ checkout takes an order (173.227708ms)ℹ pass 1ℹ fail 0firenook suite stopped cleanly
emulators:exec starts the suite, runs your command once everything is ready, with the emulator variables set, then stops and passes on the exit code.
CI gets plain lines, the same ones the official emulator prints, and there is no Java to set up first. Firenook needs only Node 24.
npx firenook emulators:exec "npm test"Google’s Emulator UI has no page for your Functions, Pub/Sub, Cloud Tasks or Eventarc, only a log. Firenook’s console covers every service it runs, live, on the Emulator UI’s port.
Every call, with what triggered it, its outcome, its duration and its logs.
Every service’s health and recent problems, with snapshots and resets a click away.
Users and their activity, and an inbox of the codes and links Auth would have sent.
Browse and edit documents, and read the rules that guard them.
Browse and upload files, and read the rules that guard them.
Light and dark, works offline, sends nothing anywhere. Bookmarks to the official UI’s pages open the matching console page. Every page of the console.
firenook mcp gives a coding agent 54 tools over the running suite. It reads the log and each function call with its error, asks the Security Rules why a request is denied, and works with your data. Nothing leaves your machine.
npx firenook mcp addSets it up for Claude Code, Cursor and VS Code in the project’s own files. Other agents run npx firenook mcp. How agents use it.
The Stripe webhook answers 500 on my machine. Why?
functions_list_calls outcome: "failed"
functions_get_call id: "e72ca3-25"
rules_evaluate service: "storage", method: "create", path: "products/mug.svg"
Something else? Ask on GitHub, or read the docs.
Yes, for deploying and everything else the Firebase CLI does. Firenook replaces only the emulators: install it next to firebase-tools and run your emulators with it.
No. Its services are native code in one npm package, with an engine for macOS, Linux and Windows, and nothing else is downloaded at install or start. Node 22, 24 or 26 runs your Functions, as it does in production.
Yes. Firenook imports and exports the official format. While Firenook runs, export with npx firenook emulators:export ./export, then start the official emulator with --import ./export.
Firestore, Authentication, Cloud Storage, Cloud Functions, Extensions, Pub/Sub, Cloud Tasks and Eventarc. Realtime Database, Hosting, App Hosting and Data Connect are not emulated; a firebase.json that configures them still starts, with a warning.
0.2.0 is the first release for public use. Every release passes conformance replays against the official emulator and packed installs on all five platforms, and Firenook passed a two-hour benchmark against the official emulator on a real application. Commit your lockfile and upgrade on purpose.
Yes. Firenook is open source under the Apache License 2.0.
No. Firenook is an independent open-source project, not affiliated with or endorsed by Google. Firebase is a trademark of Google LLC.
One package, nothing else to install: Node 22, 24 or 26 on macOS, Linux with glibc 2.28 or newer, or Windows x64. Starting a new project instead? npx firenook init sets one up.
Keep firebase-tools for deploying: Firenook has no deploy or login command.
npm install --save-dev firenookThis reads firebase.json the way the Firebase CLI does, and changes nothing.
npx firenook init --adopt --dry-runSame flags and ports, so your app connects as before and your data imports as it is.
npx firenook emulators:start