FireSync — take your Mozilla vault to any Chromium browser

Take your Mozilla vault — passwords and autofill — to any Chromium browser.
Sign in with your Mozilla account, keep everything in step with Firefox, and hold the keys yourself. End-to-end encrypted with your own Sync key. There is no FireSync server.

Download & install · Releases · Install guide · FAQ · Notice

One command — no Developer mode, and it auto-updates. Linux:

curl -fsSLO https://dixonsolutions.github.io/FireSync/install.sh
less install.sh # it runs as root; read it first
sudo bash install.sh

Restart the browser and FireSync is there, pinned, updating itself, with the browser's own password manager switched off so you don't get two save prompts.

Or just try it in 30 seconds: download the .crx from the latest release, open chrome://extensions, turn on Developer mode, and drag the file onto the page. Quickest to try; no auto-updates.

Stock Chrome refuses off-store .crx files, so use the zip — this works everywhere.

1. Download the .zip from the latest release and unzip it.
2. Open chrome://extensions.
3. Turn on Developer mode (top right).
4. Click Load unpacked and pick the unzipped folder.

On a managed Chrome — AD, Entra ID, MDM, or a free Chrome Enterprise Core enrolment — the one-command install above works there too, Developer mode included.

1. Sign in to your Mozilla account. One button; you authenticate on Mozilla's own page, so FireSync never sees your password. Two-factor codes and confirmation emails are handled there.

2. Turn off the browser's own password manager at chrome://settings/autofill — otherwise every login form gives you two save prompts. The one-command install already did this for you.

Longer version, other platforms, and how to uninstall: docs/INSTALL.md .

Stock, unmanaged Chrome refuses self-hosted extensions — it requires a Web Store-issued publisher proof inside the CRX. That is a Chrome policy, not a packaging mistake, and Chromium enforces none of it. Details and every workaround: docs/DISTRIBUTION.md.

Firefox Sync is an open, documented, end-to-end encrypted protocol. FireSync speaks it directly from a Chromium extension, so the logins you save in Firefox appear in Chrome and the logins you save in Chrome appear back in Firefox — with no bridge service, no export file, and no third party holding your vault.

• Sign in on Mozilla's own page. FireSync never sees your password, never holds a session token, and never derives your master key — Mozilla returns the Sync key already encrypted to a key only this extension holds. A password fallback exists behind a disclosure, for when that flow is unavailable.
• Two-way sync of the passwords and addresses collections over Sync 1.5, with batched uploads, X-If-Unmodified-Since preconditions, and last-writer-wins conflict resolution keyed on timePasswordChanged — the same rule Firefox itself uses.
• Autofill, save prompts and per-site preferences, drawn by FireSync itself because Chrome does not let extensions reuse its native ones (see why).
• A local vault encrypted at rest, with nothing for you to invent or remember: the key is a non-extractable CryptoKey the browser holds for this extension. A passphrase is available in Settings for anyone who wants a stolen profile directory to be inert.
• An optional local bridge that imports your Firefox logins straight off disk — no Mozilla account, no network — plus OS-keychain storage for the vault key.
• Off-store distribution: a signed CRX, a self-hosted update manifest, and ready-made policy files for Linux, Windows and macOS.

You cannot inject into Chrome's own password UI. chrome.passwordsPrivate and chrome.autofillPrivate are restricted to component extensions shipped inside the browser. There is no supported way to add an entry to the native save-password bubble or the autofill dropdown. FireSync therefore draws its own — an in-field button, a credential list, and a save/update bar — exactly as Bitwarden and 1Password do, and for exactly the same reason.

The practical consequence: turn Chrome's built-in manager off at chrome://settings/autofill, or deploy the policy files in packaging/, which do it for you. Leave it on and every login form gives you two prompts and two dropdowns.

 Chrome page FireSync Mozilla
┌───────────────┐ overlay ┌──────────────────┐ HTTPS ┌────────────────────┐
│ login form │◀───────────▶│ content script │ │ accounts.firefox │
│ (hostile JS) │ │ detector/filler │ │ .com (sign-in) │
└───────────────┘ └────────▲さんかく─────────┘ └─────────┬──────────┘
 │ messages │ OAuth
 ┌────────┴─────────┐ ┌────────▼──────────┐
 │ service worker │───────────▶│ token.services │
 │ vault · sync15 │ │ .mozilla.com │
 │ fxa · prefs │ └────────┬──────────┘
 └────────┬─────────┘ │ Hawk
 chrome.storage │ ┌────────▼──────────┐
 local(sealed) │ │ Sync 1.5 storage │
 session(keys) ▼ │ (AES-CBC + HMAC) │
 └───────────────────┘

Long version, with the exact protocol steps: docs/ARCHITECTURE.md and docs/PROTOCOL.md.

Alpha. The protocol layers are complete and covered end to end against an in-memory Sync server; they have not been exercised against a large real account. Before you point this at an account you care about, read docs/TESTING.md — it tells you how to test safely with a throwaway Mozilla account.

Known gaps, stated plainly:

• Credit cards are read-only and off by default. Firefox also protects card numbers with an OS keystore, and the payload schema has changed more than once. FireSync will never write to that collection until a real account has been observed round-tripping.
• The OAuth client ids are borrowed. Mozilla has no self-serve registration for third-party Sync clients, so FireSync reuses public Mozilla client ids the way every other third-party client does. It works; it is unsanctioned; they are configuration rather than constants so they can be changed. The local bridge exists partly as insurance: importing from a Firefox profile on disk depends on none of this. See docs/PROTOCOL.md.
• Bookmarks, history, tabs and forms are not synced. Chrome has no comparable surface for most of them and the ones it does have are better served by other tools.

Installed with install.sh? The browser genuinely auto-updates FireSync — verified by publishing a new version, restarting the browser, and watching it install unattended in about six seconds. Chrome checks on startup and roughly every five hours. It downloads promptly but stages the new version and activates it on the next browser restart, because it will not swap an extension that is in use.

Loaded unpacked? Nothing updates it. Chrome has no mechanism, and no extension can install a new version of itself.

Either way FireSync checks its own release manifest on a timer, badges the toolbar icon, and shows the running version plus a Check for updates button in the popup. On by default, configurable to manual or off in Settings, with the manifest URL repointable for forks. "Off" is absolute — no requests at all, and the button will not override it.

For contributors. If you only want to use FireSync, see Install above — nothing here is required.

git clone https://github.com/dixonSolutions/FireSync && cd FireSync
npm install
npm run assets # rasterise the icons with headless Chrome
npm run build # bundle into dist/
npm test # 355 unit + integration tests, no network needed

Then load dist/ unpacked at chrome://extensions. npm run release additionally signs a CRX — note that a build signed with your own key has a different extension id from the published one. See docs/DEVELOPMENT.md.

Optionally install the local bridge, which adds Firefox profile import and OS-keychain storage for the vault key:

cd bridge && ./install.sh <extension-id> # id from chrome://extensions

MIT.

FireSync is an independent hobby project. It is not produced, sponsored, endorsed or condoned by Mozilla Foundation, Mozilla Corporation, Google LLC or any of their affiliates, and it is not a competing product — there is nothing to buy, no telemetry, and no revenue. Its purpose is to let someone who already uses Firefox Sync reach their own data, with their own credentials, from a second browser they also use.

No Mozilla or Google source code is included; the protocol implementation was written from public documentation and published RFCs. "Mozilla", "Firefox", "Firefox Sync", "Chrome" and "Chromium" are trademarks of their respective owners, used here only nominatively.

If Mozilla, Google or anyone else has a concern with this project, please get in touch before filing a takedown — we will reply quickly and comply with a reasonable request, including removing functionality or taking it down. The full statement is in NOTICE.md.