CRX Starter FAQ

Chrome only installs .crx files that come from the Chrome Web Store; anything else is blocked with "CRX_REQUIRED_PROOF_MISSING". With CRX Starter, open the workbench, drop the .crx file into the slot, read the check, and click Allow and install. The full walkthrough is in our step-by-step guide.

Yes, for packages you run through CRX Starter. CRX Starter itself comes from the Chrome Web Store, and the package you drop in runs inside it — so Developer Mode stays off and Chrome doesn't show the "Disable developer mode extensions" warning when it starts.

Yes. Drop the .zip as it is — there's no need to unzip it first. CRX Starter looks for manifest.json inside the archive. If it can't find one, it tells you "This isn't an extension package" before anything is installed.

A .crx file is as safe as the person who made it. CRX Starter can't vouch for a package, but before you allow it, it lists in plain words which sites it can access, which browser features it uses and what it keeps for itself. If a note-taking tool asks for every website, that's worth asking about. More in our safety notes.

Drop the package into CRX Starter and stop at the check. Everything it uses is listed in three groups — sites it can access, browser features it uses, and its own settings only — each with a count and one plain sentence. Nothing is installed until you click Allow and install, and Cancel throws the check away.

Since Chrome 75, a .crx must carry the Chrome Web Store's signature to be installed directly. Files packed by a developer or downloaded from elsewhere don't have it, so Chrome refuses them. CRX Starter doesn't need that signature because it opens the package itself.

No. Chrome itself no longer runs MV2 extensions, so if you drop an MV2 package, CRX Starter stops after reading it and says "Old-format (MV2) extensions aren’t supported". Nothing is installed and no permissions are requested — ask the author for an MV3 version.

Not right now — CRX Starter runs one package at a time. If you drop in another one, the check says "Installing this replaces …" and the button becomes Replace and install; the current one and its data are cleared first.

Only when you installed from a link that includes an update address. CRX Starter checks it once a day, and you can press Check for updates in the workbench any time. Packages installed from a file don't update — drop the new version in.

Because it isn't installed as a separate Chrome extension; it runs inside CRX Starter. Open the CRX Starter workbench to open it, change its settings, check for updates or remove it.

A few Chrome features — such as bookmarks, history and the debugger — can't be passed through to a package running inside CRX Starter. The check lists these under "May not work" before you install. If something else is broken, tell us from the feedback page.

Open the workbench, click Remove and confirm — the package's files and data are cleared, and the toolbar icon goes back to CRX Starter's own. To remove CRX Starter, right-click its toolbar icon and choose Remove from Chrome.

If you still have its .crx or .zip, you can drop it on CRX Starter like any other package, as long as it's Manifest V3. Think about why it was removed before you do — the check will show you what it can access.

No. CRX Starter is an independent extension. Chrome and Chrome Web Store are trademarks of Google LLC.

A .crx file is how Chrome packages an extension: a ZIP archive with a signed header in front. Chrome uses the signature to check who made it, and since version 75 it only installs .crx files signed by the Chrome Web Store directly. More in what is a CRX file.

From the Chrome Web Store, click Add to Chrome. For a package from anywhere else, Chrome's own route is Developer Mode: unzip it, open chrome://extensions, turn on Developer mode and click Load unpacked — Chrome then warns you about it on every start. With CRX Starter you drop the .crx or .zip into the workbench instead and read the check before installing.

Usually one of three reasons: the file isn't from the Chrome Web Store, so Chrome refuses it; the extension is old-format (MV2), which Chrome no longer runs; or your device is managed by a school or employer that blocks extensions. CRX Starter can help with the first one. For the third, ask your administrator — CRX Starter isn't a way around their rules.

Click Send feedback at the bottom of the workbench, or email us. The workbench shows a Feedback ID you can copy — include it and we can find what happened faster.