5 Tips to Select Right Browser List for Cross Browser Testing

1. Based on Popularity of Browsers and Devices

Each day a new update knocks the door of technology. Whether it's a newer version of an already existing application or a completely new application, we need to consider it all.

The question that comes here is 'Do we need to test them too?'. Let's take it objectively. We cannot test on each and every one of browsers and devices that can be used to access the internet.

For example, a typical desktop list is the last few stable versions of Chrome, Edge and Firefox on Windows, plus Safari and Chrome on macOS. On mobile it usually comes down to Chrome on Android, Safari on iOS and Samsung Internet on Galaxy devices.

Popularity also varies by region. A browser that leads in North America does not automatically lead in Europe or in India, and locally popular devices ship their own default browsers. Check the share for the countries your traffic comes from instead of the global average.

You can stay up to date on browser and device popularity by following statcounter, w3c, wikimedia, and its user agent breakdowns. Pull those numbers again every time you revise the list, because published charts age fast.

Group the list by rendering engine before you count browsers, because cross browser compatibility follows the engine and not the brand name. Chrome, Edge, Opera and Samsung Internet all run on Chromium. Firefox runs on Gecko, and Safari runs on WebKit. Browsers on iOS render with WebKit too, so a layout bug in Chrome for iOS is usually a WebKit bug and Safari will show it as well. Cover one browser per engine first, then add the specific versions your traffic uses. That keeps the matrix small without leaving a rendering engine untested.

Key Takeaway: Browser popularity shifts by region, so a browser list should follow the usage share of the countries the traffic actually comes from and cover one browser per rendering engine before adding individual versions.

2. Using Google Analytics For Targeting Devices

Google Analytics 4 tells you which browsers your own visitors use. The Tech details report under Reports and then Tech breaks traffic down by browser, browser version, operating system, screen resolution and device category. Sort it by users or by conversions and you get a priority order that comes from your audience rather than from a global chart. The more traffic a configuration brings, the earlier it belongs in your test run.

For most sites Chrome sits at the top of that report and gets tested first. The useful part is the long tail below Chrome, because it tells you where your list can stop.

If you are more conversion oriented you can also develop a strategy based on the number of clicks, goal conversions and even bounce rates. You can then set the priority for your testing and formulate a perfect cross browser testing strategy.

GA4 also segments the audience by location, demographics and interests. Read those reports next to the tech reports and you can build a list of browsers and devices that deserve the highest testing priority.

Key Takeaway: The Google Analytics 4 Tech details report ranks browsers, versions and devices by real users and conversions, which sets the testing order and shows where a browser list can safely stop.

3. Test The Older Ones Too!

Not everyone stays up to date with the latest browser releases. Many people still run the default browser and the browser version that shipped with their operating system. Internet Explorer 11 is no longer part of that problem, because Microsoft retired it on 15 June 2022 and permanently disabled the desktop application through an Edge update in February 2023. The legacy work has moved to IE mode in Edge and to the older Chrome, Firefox and Safari builds that managed devices stay pinned to.

Many users cannot or would not update their browsers especially enterprise users who are using very secure machines or browser dependent enterprise apps.

All this makes older versions part of your compatibility testing rather than an optional extra. You can prioritize the exact versions based on your traffic, audience analysis, and user feedback.

Give the list a review date instead of leaving it fixed for years. Chrome, Edge and Firefox each ship a new stable release about every four weeks, so a list written a year ago names versions almost nobody runs today. A quarterly review is enough for most teams. Pull the last 90 days of traffic, drop any version that fell below your support threshold, add the new stable releases, and check the features you depend on against the Baseline support data on MDN before you promise support for an older browser.

Agree on what supported means for each browser before you extend the list. The MDN guide to cross browser testing states that a site does not need to deliver the exact same experience on all browsers and devices as long as the core functionality is accessible in some way, and that the developer and the site owner should agree on the range of browsers and devices where the code will work. Write that agreement down and an older browser can stay on the list for core flows only, instead of holding every release to a pixel match nobody asked for.

Key Takeaway: Older browser versions belong on a browser list because enterprise machines stay pinned to them, and a quarterly review of the last 90 days of traffic keeps the named versions current.

4. Educated Guesses Based on Audience

Experience matters. There are a number of factors that define an audience's consumption of your website. If you are media website, mobile browsers are a priority for you, similarly if you are B2B oriented webapp, desktop chrome and firefox browser are your priority.

Some call it common sense and just leave it at that, however I believe that each assumption can be backed by data. The only challenge is to seek the answers to the right questions.

• What is your audience's demographics?
• What is the preferred media accessing device of your targeted demographics?
• What is the location of your audience? What devices are popular in those locations?
• What is the problem your app can solve for your users and how your app can best solve it?

Key Takeaway: Audience type shapes a browser list, so a media website prioritizes mobile browsers while a B2B web app prioritizes desktop Chrome and Firefox, and every such assumption should be backed by demographic and location data.

5. Support Issues

Your customers may mention few browsers or devices which creates problem again and again. These Issues need to be resolved at its latest so should be kept at its highest priority list of testing.

Key Takeaway: Browsers and devices that customers report problems on repeatedly belong at the top of a cross browser testing priority list.

How Do You Turn Your Browser List Into a Config Your Tools Can Read?

Write the finished list into a Browserslist config so the build and the test matrix read one definition instead of two. Browserslist lives in a .browserslistrc file or in a browserslist key inside package.json, and it records the decision as queries such as last 2 versions, not dead and Firefox ESR.

Autoprefixer, babel-preset-env, postcss-preset-env, eslint-plugin-compat and stylelint-no-unsupported-browser-features all read that same config. The CSS you ship, the JavaScript you compile and the lint warnings you see then line up with the browsers you agreed to support, so a browser cannot quietly sit on the test matrix while the build has already dropped it. Browserslist also accepts baseline widely available as a query. A feature reaches widely available Baseline status 30 months after it becomes interoperable across Chrome, Edge, Firefox and Safari, so that query ties your targets to a published support rule rather than to version numbers you chose by hand.

You can point the same queries at your own traffic. Save your usage numbers as browserslist-stats.json and a query like cover 99.5% in my stats resolves against your visitors instead of global share. The browserslist-ga and browserslist-ga-export tools generate that file from Google Analytics data. Check the export before you trust it. Google Analytics 4 automatically excludes traffic from known bots and spiders, and Google states that you cannot disable that exclusion or see how much was removed, so your numbers are already cleaned of the crawlers it recognizes but not of anything it does not. Review the config on the same schedule as the list itself, and the browsers your build targets and the browsers your tests cover stay in step.

Key Takeaway: A Browserslist config in .browserslistrc or package.json gives the build and the test matrix one shared browser definition, and Autoprefixer, babel-preset-env, postcss-preset-env, eslint-plugin-compat and stylelint-no-unsupported-browser-features all read the same config.

How Do AI Agents Change the Browser List You Test?

AI agents usually drive fewer browsers than your list names, so check which engine the agent actually launched before you count its run as coverage. The browser list stays the source of truth and the agent is one more row in it.

Google publishes chrome-devtools-mcp, which lets a coding agent control and inspect a live browser. Its documentation states that the project officially supports Google Chrome and Chrome for Testing only, and that other Chromium based browsers may work but are not guaranteed. An agent wired to it reports on Chrome, not on the rest of your matrix.

Microsoft publishes Playwright MCP, which drives the page through the Playwright accessibility tree rather than pixel based input, and takes a browser option of chrome, firefox, webkit or msedge. Its Docker image supports headless Chromium only, so an agent running in a container covers one engine whatever the option says.

Engine coverage is also not browser coverage. The Playwright browser documentation states that Playwright does not work with the branded version of Safari, and that its WebKit build comes from the WebKit main branch, often before those updates reach Apple Safari. A passing WebKit run is evidence about WebKit, not proof that Safari on an iPhone renders the page the same way. Branded Chrome and Edge are reachable only through the channel option.

Record which engine, channel and build every browser automation run used, and keep the rows the agent cannot reach on a real browser run. An agent can write and repair the test code, but it cannot tell you which browsers matter. That answer still comes from your own traffic.

Key Takeaway: An AI agent covers fewer browsers than a browser list names, because chrome-devtools-mcp officially supports Google Chrome and Chrome for Testing only and the Playwright MCP Docker image supports headless Chromium only.