---
title: "Migrate from Firebase"
description: "Move Firestore, Firebase Auth and Storage calls onto MainSDK db, auth and files, with the codemod, the report and a pull request."
section: "guides"
status: "Planned for 0.7"
spec: "migration-guides"
canonical: "https://mainsdk.dev/docs/guides/migrate-from-firebase"
updated: "2026-10-28"
---

# Migrate from Firebase

> Move Firestore, Firebase Auth and Storage calls onto MainSDK db, auth and files, with the codemod, the report and a pull request.

Status: Planned for 0.7 · Canonical: https://mainsdk.dev/docs/guides/migrate-from-firebase · Updated: 2026-10-28

Move Firestore, Firebase Auth and Storage calls onto MainSDK db, auth and files, with the codemod, the report and a pull request. Your Firebase account stays; nothing here deletes it.

**Before you start:**

- A git repository with a clean working tree. `mainsdk migrate` works on a branch and never touches yours.
- Node 22 and `npx mainsdk`. No `main.yaml` yet? `migrate` writes one; or start with [Adopt an existing app](https://mainsdk.dev/docs/getting-started/existing-app).
- Your Firebase keys stay where they are. Move them to `secret:` references when the driver is chosen (see [Secrets](https://mainsdk.dev/docs/interfaces/secrets)).

## 1. Read the report

```text
npx mainsdk migrate firebase --report-only
```

The report writes no file. It sorts every Firebase call in your code into three lists: **mapped** (an interface call replaces it), **raw** (it stays behind `raw()`, with the reason) and **needs a person** (a policy, a rule file or a call with no interface). Add `--json` for a machine-readable report.

For the sample app of this guide (`packages/cli/test/fixtures/migrate/firebase`), the report finds 4 mapped, 1 raw and 1 for a person.

## 2. What the codemod changes

| Where | Before | After |
| --- | --- | --- |
| `lib/auth.ts:5` | `signInWithEmailAndPassword(auth, email, password)` | `auth.signIn()` |
| `lib/orders.ts:4` | `export const listOrders = () => getDocs(collection(db, 'orders'))` | `db.orders.for(user).list()` |
| `lib/orders.ts:6` | `export const addOrder = (row: unknown) => addDoc(collection(db, 'order` | `db.orders.for(user).create()` |
| `lib/orders.ts:8` | `export const removeOrder = (id: string) => deleteDoc(doc(db, 'orders',` | `db.orders.for(user).remove(id)` |

Each rewrite is mechanical and one line at a time. Imports of Firebase go when no call needs them, and `mainsdk` is added to `package.json`.

## 3. What stays behind raw()

- `lib/live.ts:3`: no realtime listener capability: onSnapshot

A call behind `raw()` keeps working through the `Firebase` host on your network allow list, and `mainsdk check` still sees it. Each one has a marker comment, `// mainsdk migrate: ...`, so you can find it later.

## 4. What needs a person

- `firestore.rules:1`: security rules need a data label owner

The codemod leaves these lines alone and marks them. No tool should guess a policy.

## 5. Stateful moves are guided jobs

Data does not move with the code. Each stateful move is a job with steps and a rollback, listed in the pull request and never run by the codemod.

### users: Move Firebase Authentication users

1. Run firebase auth:export users.json (password hashes come with the project hash parameters).
2. Import into the new auth driver on staging and compare counts.
3. Switch auth.driver for 1% of sign-ins, then all.

Rollback: Set auth.driver back to firebase; Firebase keeps its users until the project is deleted.

### documents: Copy Firestore collections to the app database

1. Export each collection named in the report with gcloud firestore export.
2. Load it into the new database and run the document-count check.
3. Dual-write for one week, then read from the new database.

Rollback: Point db.driver back at Firestore; the dual-write kept it current.

## 6. Open the pull request

```text
npx mainsdk migrate firebase
```

This records your sign-in and checkout flows as locked flows first, then creates the branch `migrate/firebase`, applies the codemods, adds `.github/workflows/mainsdk-migrate.yml`, runs `mainsdk check` and the locked flows, commits, pushes and opens one pull request with `gh`. If a gate fails, the branch is kept and no pull request opens (`MAIN-MIGRATE-0001`). `--no-pr` stops after the commit.

Locked flows run again in CI: `npx mainsdk migrate flows`.

## Where you end

You end at the reference architecture [`mainsdk/saas-web`](https://mainsdk.dev/docs/guides/reference-saas-web): the same shape, with its tests, benchmark and chaos drills.

```text
npx mainsdk init --template mainsdk/saas-web
```