What is Chrome extension testing?

Chrome extension testing checks that a browser extension works as intended, and that a site still behaves correctly while that extension is installed. On TestMu AI you load an extension into a live Chrome session running on a Windows or macOS virtual machine, then test with it switched on across Chrome 37 to 153.

How do I test a Chrome extension?

Load the extension into a live Chrome session running in the cloud instead of installing it locally. Choose Chrome, a Chrome version and an operating system, open the Chrome Extension panel in advanced settings, paste the extension's Chrome Web Store URL, then switch it on. It installs while the browser boots, before the site loads.

Can I load a Chrome extension into the session?

Yes, on desktop sessions. Open the Chrome Extension panel in the session configuration, paste the extension URL, and the extension loads with the browser when the session starts. An extension can also be added while a session is already running. Full steps are in the pre-loaded Chrome extension documentation.

Can we pre-load extensions so testers do not add them every time?

Yes. An extension saved to the account stays there and attaches automatically before every desktop Chrome session, so testers stop re-adding the same extension on each new virtual machine. Saved extensions can be switched on and off per run.

Can I load an unpacked extension or a local .crx build?

No, not by any documented method. Extensions are added by pasting a Chrome Web Store URL, so a published extension is the supported path. Uploading an unpacked build or a local .crx file is not documented. Teams testing an extension before release should confirm with support first.

Which Chrome versions can I test a Chrome extension on?

Chrome 37 through the latest stable build, which is 153 as of September 2026, with 154 in Beta. That range covers both a current release and the older Chrome builds some users still run, so one extension can be checked against both from the same account.

How many extensions can I save?

There is no documented cap. Save the extensions your team works with and switch on only the ones a given run needs, since each saved extension has its own toggle. Extensions stay on the account between sessions, so the list is built once and reused.

Why are Chrome extensions not available in my mobile session?

Chrome extension loading runs on desktop sessions only, on Windows and macOS virtual machines. Mobile and ChromeOS sessions do not support it, and the pre-load panel is Chrome rather than Firefox, Edge, or Safari. You can still install add-ons by hand inside a live Firefox session, because that is a real browser.

My session ended on its own. Why?

Either the idle timeout fired or the session hit its cap. The idle timeout defaults to five minutes and is configurable in the session Settings panel, so raise it in your first session. Manual sessions also stop at a two hour maximum, after which you start a new one and carry on.

What happens to my screenshots when a session ends?

They are kept. Screenshots and recordings save to the session Gallery and stay downloadable after the session closes. The virtual machine itself is wiped, so anything created inside it and never captured is gone. Export anything an audit depends on rather than relying on the Gallery.

My session will not start or keeps disconnecting. What is it usually?

Blocked WebSockets, in nearly every documented case. Session rendering runs over WebSockets, so a network or a local browser that blocks them will stop a session starting or hold it open. Run a public WebSocket echo test to confirm, ask your network admin to open WebSockets, and reach the platform on the latest Chrome.

Is this the same as the TestMu AI Chrome Extension?

No, the two solve opposite problems. Chrome extension testing loads your own extensions into a cloud browser session. The TestMu AI Chrome Extension is an extension installed in your own browser to launch live tests across 3,000+ browsers and operating systems.

Chrome Extension Testing in a Real Chrome Session

Load your site in a real Chrome with your own extensions switched on. Test across Chrome 37 to 153 on Windows and macOS. Free to start.

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Chrome Extension Testing in a Real Chrome Session

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Your Extensions, On Every Chrome Version We Run.

Save an extension once, pick the Chrome version and OS you need, and run the ad blockers, debuggers, and accessibility tools your team already uses.

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Add an extension once, not every session

Save an extension to your account and the whole team opens sessions with it already on. Each session spins up a fresh virtual machine, and your saved list is there too.

Start testing with your extensions free

Save as many extensions as your team uses
Switch on only the ones a given run needs
Add one mid-session if you forgot to load it
Your saved list carries into every new session

Chrome Extension panel in a Real Time session showing a saved extension with an on-off toggle and a field to paste an extension URL

Pick the Chrome version, OS, and resolution you need

Change the Chrome version, the OS, or the resolution and your extensions load with it. Reproduce a reported bug on the exact Chrome build it was found on.

Pick a Chrome version and test

Chrome 37 to the latest stable, 153 as of September 2026, plus Beta
Windows 11 back to Windows 7, macOS Golden Gate back to Catalina
Screen resolutions from 1024x768 to 1920x1080

Session configuration showing Windows and macOS versions, the browser list with Chrome versions, and the Chrome Extension dropdown

Run the extensions your team already uses

Ad blockers, password managers, debugging add-ons, and accessibility tools all run inside the session. Whatever your team already relies on comes along.

Start a session with your extensions

See what breaks with an ad blocker running
Check autofill with a password manager loaded
Debug with Lighthouse, React DevTools, or Web Developer
Audit accessibility with Axe or WAVE beside NVDA

Real Time desktop session showing the Chrome Extension panel, the browser list, and an Accessibility screen reader panel

Test with extensions loaded, without a local setup

Network Throttling

Drop the session to a slow connection and watch how an extension-heavy page behaves when requests start queuing.

Full Session Recording

Start and stop a video of the run, so an extension bug that only appears once is captured the first time it happens.

One-Click Bug Logging

Mark as Bug captures an annotated screenshot and pushes it to Jira, Azure DevOps, or GitHub Issues with the browser and OS attached.

A Clean Profile Every Run

Ending a session wipes the machine, so no cached extension state, cookies, or stored permissions carry into the next test.

Local and Private Builds

Switch on the tunnel and the session reaches a locally or privately hosted app, so extensions get tested before the build ships.

Network Request Logs

See exactly which requests an ad blocker killed, and which ones an extension added, without leaving the session.

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