Drumline Digital | Metronome Extension

Metronome enables QA by applying a query parameter to the end of a target URL which is set as an audience in your experimentation platform. The audience is used to limit who can qualify for tests that are live on that page to users with the URL parameter. Metronome makes enabling and disabling that audience easier and consistent across multiple navigations by ensuring the QA audience is consistent during a session.

Benefits

Using Metronome ensures your QA process reflects real-world conditions. At Drumline, we advocate for query parameter-based testing to:

• Enter experiments only if the user meets actual targeting criteria – unlike preview links which may bypass them.

• Validate metric tracking in real time – testers' actions fire off events visible in reporting, which are cleared before launch.

• Test traffic distribution accurately across variations.

• Metronome is tool-agnostic – Use it with any experimentation platform.

• QA mobile experiences easily – just scan a QR code to view the test on your phone.

• Metronome evolves with you – Metronome receives regular features and fixes. Updates are automatically applied, ensuring you always have access to the latest functionality.

Limitations

While Metronome is powerful, it's still evolving. Current limitations include:

• Variation Lock-in – Just like in production, you will get stuck in varaitions. This can mean you are stuck in 'Control'. Clear your cookies to be re-allocated.

• Chrome based browsers only – Metronome is currently supported in browsers built on Chrome, such as Chrome, Edge, and Brave. It isn’t compatible with Firefox, Safari or other non-Chromium browsers.

• Mobile browsers do not support extensions – Metronome is a desktop extension. Mobile browsers don’t support extensions, so it won’t work on phones or tablets.

Features

Metronome offers the following key features:

• QA Mode Toggle – Easily enable or disable QA mode from any test-targeted page.

• URL Query Injection – Appends ?drumline-qa-mode=true to the URL to enter QA mode.

• Mobile Testing via QR Code – Scan a QR code to load a test experience on your mobile device.

^{Scan the test specific QR code to open the page on your mobile device and QA the experience in real conditions.}

Installing Metronome

1. Open the Chrome Web Store link.

2. Click “Add to Chrome”.

3. Confirm by selecting “Add Extension” in the pop-up.

4. Done!

Metronome works with other Chrome based browsers, too. Follow these steps in Edge, Brave and any other browser based on Google Chrome.

Make it Easy To Find

Make the Metronome icon appear next to your address bar.

1. Click the puzzle piece icon in the Chrome toolbar

2. Click the pin next to Metronome for easy access.

Access Metronome in Incognito

Enabling Metronome in Incognito mode lets you QA experiments in a clean testing environment — without cached data, cookies, or saved sessions interfering.

1. Go to the Chrome '3 dot' menu in the top right of your browser

2. Find Extensions → Manage Extensions

3. Locate Metronome and click Details

4. Enable “Allow in Incognito” if needed.

Using Metronome

Enable QA Mode

Enable qualifications for experiments that are not published to everyone – review and debug experiences.

1. Navigate to a page targeted by a QA experiment.

2. Click the Metronome icon in the Chrome Extensions bar.

3. In the popup, enable QA by clicking the switch so it turns Green.

The page will reload and the URL will update with ?drumline-qa-mode=true applied. You can now interact with the experience as a real user would – check visuals, functionality, and event tracking.

^{Shows the Metronome tool with QA mode enabled.}

Disable QA Mode

Disable qaulifcations for experiments that are not published to everyone – see production experiments; what everyone would see

1. Click the Metronome icon in the Chrome Extensions bar.

2. In the popup, disable QA by clicking the switch so it turns Red.

The page will refresh and the URL will update with ?drumline-qa-mode=true removed – this removes you from any live QA experiences.

^{Shows the Metronome tool with QA mode disabled}

See it in Action!