How to Install a CRX File in Chrome (2026)

CRX Starter Team · Updated Oct 31, 2026 · 5 min read

Short answer

Chrome only installs .crx files signed by the Chrome Web Store, so dragging one onto chrome://extensions usually fails with CRX_REQUIRED_PROOF_MISSING. To run it anyway, add the free CRX Starter extension, open its workbench, drop the .crx file into the slot, review the check, and click Allow and install. No Developer Mode needed.

A coworker sends you ticket-peek-1.4.0.crx, the little helper the support team uses to preview tickets. You drag it onto chrome://extensions and Chrome answers with "Package is invalid: CRX_REQUIRED_PROOF_MISSING". Nothing is wrong with the file — Chrome simply refuses .crx files that didn’t come from the Chrome Web Store.

This guide shows the route that works in current Chrome without switching on Developer Mode: run the package inside CRX Starter, and read what it uses before anything is installed.

Transcript

01You downloaded a .crx file, and Chrome says no.
02Step one. Add CRX Starter from the Chrome Web Store.
03Step two. Click its icon, then Open workbench.
04Step three. Drop the file into the slot.
05Step four. Read the check. It comes from a local file, so it won't update by itself.
06It uses one support site, your tabs, and storage for its own settings.
07Step five. Allow and install, then allow Chrome's own prompt.
08Installed. Open it from the toolbar, or remove it later from the workbench.
09CRX Starter. Read first, then install.

On this page

What you need
Steps
Why Chrome blocks .crx files
The old way: Developer Mode
If the extension was removed from the store
Removing it later
Questions

What you need

Chrome 120 or later on Windows, macOS, Linux or ChromeOS
The .crx file — it must be a Manifest V3 extension
About two minutes

Steps

1
Add CRX Starter from the Chrome Web Store
CRX Starter is a free extension that runs packages from outside the store. Because CRX Starter itself comes from the Chrome Web Store, Chrome trusts it — and Developer Mode can stay off.
2
Open the workbench
Click the CRX Starter icon in the toolbar and choose Open workbench. Don’t see the icon? Click the puzzle icon and pin CRX Starter. The workbench opens in a tab: a drop slot on the left, and an empty label on the right.
3
Drop the .crx into the slot
Drag ticket-peek-1.4.0.crx onto the slot that says Drop a .crx or .zip here, or click Choose file. CRX Starter opens the package in your browser — nothing is uploaded — and the progress list moves from Read to Check: "manifest read", then "Waiting for you".
4
Read the check
The check is the white label on the right. It shows where the package came from (Local file), whether it can update itself (No: local files have no update address), and under What it uses every permission in three plain groups, each with a count: Sites it can access, Browser features it uses and Its own settings only.
Ticket Peek lists one site (support.acme-desk.example), one browser feature (tabs) and one of its own settings (storage). That matches a ticket-preview tool. If you want to know what each group means, read the three permission groups before you go on.
5
Allow and install, then confirm Chrome’s prompt
Click Allow and install. If the package needs something CRX Starter hasn’t been granted yet, Chrome shows its own permission prompt — that is the step that actually grants access. Allow it, and the label switches to Installed. with the status Running.
Click the CRX Starter icon in the toolbar and Ticket Peek’s own popup opens. Its settings are under Settings in the workbench.

Why Chrome blocks .crx files

Since Chrome 75, a .crx file must carry a signature from the Chrome Web Store before Chrome will install it directly. Files packed by a developer, exported from another browser or saved from an old download don’t have that proof, so Chrome stops with CRX_REQUIRED_PROOF_MISSING. The rule protects people from extensions slipped in by other software — and it also blocks the internal tools and test builds you actually meant to run. If you want the full story, here is why Chrome rejects the file.

The old way: Developer Mode

Chrome’s own workaround is to unpack the .crx (rename it to .zip and extract it), open chrome://extensions, switch on Developer mode and click Load unpacked — here is the Load unpacked route step by step. It works, but it has costs: you have to keep the unpacked folder forever, Chrome can warn you about developer-mode extensions when it starts, and at no point does it explain in plain words what the extension can do.

	Developer Mode	CRX Starter
Accepts a .crx as it is	No — unpack it first	Yes
Developer Mode switched on	Yes	No
Permissions explained before install	No	Yes — sites, browser features, own settings
Folder you must keep on disk	Yes	No
Shows in chrome://extensions	Yes	No — managed in the workbench

If the extension was removed from the store

People often keep a .crx of an extension that later disappeared from the Chrome Web Store. If it’s Manifest V3, CRX Starter installs it the same way. Before you click, think about why it was removed: store takedowns happen for policy and security reasons as well as for abandoned projects. The check shows you exactly what it uses.

Manifest V2 packages won’t run. If the check stops with "Old-format (MV2) extensions aren’t supported", nothing is installed and no permissions are requested. Ask the author for an MV3 version.

Removing it later

Open the workbench and click Remove, then confirm. The package’s files and the data it saved are cleared, and the toolbar icon goes back to CRX Starter’s own. To install a different package, just drop it in — CRX Starter runs one package at a time and asks before replacing the current one.

Got a .crx Chrome won’t take?

Add CRX Starter, drop the file in, and read the check before you say yes.

Add to Chrome — It's Free

Questions

Can I just double-click a .crx file?

No. Double-clicking usually opens it as a download or does nothing, and dragging it onto chrome://extensions fails with CRX_REQUIRED_PROOF_MISSING unless it came from the Chrome Web Store. Drop it into the CRX Starter workbench instead.

What if it’s a Manifest V2 package?

CRX Starter reads it and stops with "Old-format (MV2) extensions aren’t supported". Chrome no longer runs MV2 extensions at all, so the only fix is an MV3 version from the author.

Will it update itself?

Not when you install from a file — local files have no update address. Drop the new version in when the author sends one. Packages installed from a link with an update address are checked once a day.

Read next

Guide · 5 steps · 5 min readInstall a Chrome Extension From a ZIP (No Unzipping)A ZIP from a GitHub release? Drop it in as-is — no unzipping, no Developer Mode.Guide · 3 steps · 7 min readChrome Extension Permissions: How to Check Them Before You InstallEvery Chrome extension permission in plain words — and one question: does what it uses match what it’s for?Note · 5 min read"CRX_REQUIRED_PROOF_MISSING": What It Means and What to DoChrome refused a .crx with "Package is invalid: CRX_REQUIRED_PROOF_MISSING". Why it happens, and four ways forward.