How to Enable Developer Mode in Chrome and Load an Unpacked Extension

What Does Developer Mode Do in Chrome?

Developer Mode is a setting on the chrome://extensions page that lets Chrome install extensions from a local folder instead of only from the Chrome Web Store. It's the switch behind every developer tools extension before it's published anywhere.

You don't need it to use extensions from the Chrome Web Store — only to load unpacked source code, install a .crx file directly, or run a Tampermonkey script that lives on your disk instead of in a store listing.

• You're building your own extension and want to see changes without publishing anything.
• A developer sent you a .zip or a GitHub link to test a build before it's listed.
• You're following a coding tutorial that has you load a sample folder as you go.
• You need a fix or a feature the published version of an extension doesn't have yet, and a maintainer has shared an unreleased branch.

How Do You Turn On Developer Mode in Chrome?

Turn on Developer Mode by opening chrome://extensions and flipping the toggle in the top-right corner of the page — it takes four clicks and Chrome doesn't ask you to confirm or restart.

1. Open a new tab and type chrome://extensions in the address bar, then press Enter.
2. Look at the top-right corner of the page for a toggle labeled Developer mode.
3. Click the toggle so it turns on. The change applies immediately, with no confirmation dialog.
4. Three new buttons appear at the top of the page: Load unpacked, Pack extension, and Update.

Once an unpacked extension is loaded, Chrome adds a persistent banner reading something like "Disable developer mode extensions," with a button to turn Developer mode off in one click. That's expected — it's the same reminder every profile with an unpacked extension gets, not a sign anything is wrong.

How Do You Load an Unpacked Extension in Chrome?

Loading an unpacked extension means pointing Chrome at a folder that contains a manifest.json file, with Developer mode already switched on.

1. Get the extension's source folder onto your computer — downloaded, cloned from GitHub, or unzipped — so it contains a manifest.json file at its top level.
2. With Developer mode on, click Load unpacked on the chrome://extensions page.
3. In the file picker, select the folder itself, not the manifest.json file and not a parent folder above it, then click Select Folder.
4. Chrome adds a card for the extension immediately, with no reload needed. If the icon doesn't show in the toolbar, click the puzzle-piece icon and pin it.
5. After you edit the code, return to chrome://extensions and click the circular Update icon on the extension's card to load your changes.

Click Details on the extension's card to reach two toggles worth knowing about: Allow access to file URLs, needed if the extension has to read local file:// pages, and Allow in Incognito, off by default for every extension including unpacked ones. Neither is required just to load and test a typical extension.

To debug the code itself, click Inspect views: service worker (or background page on older manifests) on the extension's card. That opens a dedicated DevTools window with console.log output and breakpoints for the extension's background script, separate from the DevTools you'd open on a normal web page.

Load Unpacked vs Installing From the Chrome Web Store: What's the Difference?

Load unpacked installs whatever is in a folder, with no review. Installing from the Chrome Web Store installs a reviewed listing that updates itself. Here's how the two compare.

There's no in-between setting that gives you automatic updates without a store listing, and no way to submit an unpacked folder for review without going through the normal Chrome Web Store developer registration first. If an extension is genuinely useful past your own testing, publishing it is what gets it automatic updates and out of the Developer mode warning banner for anyone else who installs it.

What Do You Do When Chrome Won't Load Your Unpacked Extension?

Most load failures come down to picking the wrong folder or an outdated manifest. Here's what each error actually means and how to fix it.

If an extension loads without an error but simply doesn't do anything, check the Inspect views link on its card first — a broken background script often fails silently with nothing visible except a stack trace in that console. A stale cached copy of the folder can also cause odd behavior; removing the extension and loading it fresh usually clears that.

Why Does Chrome Warn That Developer Mode Extensions Can Harm Your Computer?

Chrome shows that warning because Developer Mode installs skip the Chrome Web Store's review process entirely — nothing has checked the code but you. The banner isn't a bug; it's Chrome being upfront about what Developer mode actually removes.

Unpacked extension

An extension loaded from a folder on disk instead of installed from a packaged .crx file or the Chrome Web Store.

manifest.json

The required file at the root of an extension's folder that declares its name, version, permissions, and entry points.

Extension ID

The unique string Chrome generates for each extension; unpacked extensions can get a new ID if you move or re-select the folder.

Pack extension

A Developer mode button that bundles a folder into a distributable .crx file plus a .pem private key.

Service worker

The background script that runs an extension's logic outside any web page; Manifest V3 extensions use one instead of a persistent background page.

Allow access to file URLs

A per-extension toggle, off by default, that lets an extension read local file:// pages instead of only http and https ones.

The warning also shows up because Chrome can't apply the same automatic malware scanning to an unpacked folder that it runs against every Chrome Web Store submission. That scanning, along with the human policy review, is what normally catches an extension that requests far more access than its description explains — an unpacked build simply hasn't been through it yet, no matter how trustworthy the source looks.

If you're weighing an unpacked build against a published listing, check what the permission actually allows before you decide — the risk is almost always in the permissions requested, not the installation method itself.

Does Developer Mode Work the Same Way on a Chromebook or Android?

No — browser-level Developer mode and ChromeOS's own Developer Mode are two different things that happen to share a name. The chrome://extensions toggle only changes how the browser installs extensions. Switching a Chromebook itself into Developer Mode is a device-level change that wipes local data and needs a full powerwash to undo.

On a Chromebook, the browser toggle works exactly as described above — load unpacked extensions the same way you would on Windows or Mac. See our Chromebook extension picks for what's worth installing day to day, alongside anything you build yourself.

Chrome for Android and Chrome for iOS don't support extensions at all, with or without Developer mode — there's no chrome://extensions page on either mobile app. If you need extension-like features on a phone, see what's actually possible with Chrome extensions on Android and iPhone instead of hunting for a mobile developer toggle that doesn't exist.

A Chromebook running the Linux (Crostini) container is a partial exception worth knowing about: code you edit inside that container and load unpacked into the regular Chrome browser behaves exactly like it would on desktop Chrome elsewhere, since it's still the same desktop-class browser under the hood.

Which Extensions Are Worth Installing Once Developer Mode Is On?

A handful of ordinary, Chrome Web Store extensions make building and debugging your own code faster once Developer mode is on. None of these need to be loaded unpacked — install them the normal way.

Should You Turn Developer Mode Off When You're Done?

Not necessarily — leaving Developer Mode on indefinitely doesn't slow Chrome down or expose anything by itself. The actual risk is whatever unpacked extension you loaded while it was on, not the toggle.

To turn it off, go back to chrome://extensions and click the same toggle. Chrome keeps any unpacked extensions installed; it just hides the Load unpacked, Pack extension, and Update buttons until you switch it back on.

Turning Developer mode off does disable any unpacked extensions that are still loaded — their cards stay on the page but show as inactive, since Chrome won't run code it can no longer let you reload or inspect. Switch the toggle back on and they reactivate exactly as they were, with no need to load them again.