Inspecting and debugging mobile websites

Mobile devices are increasing becoming the key method that the world's population uses to access the internet; the global number of users accessing the web via their mobile phone or tablet first overtook desktop usage in 2014 and the gap has continued to slowly grow throughout 2015. With these stats in mind it's clear just how important a mobile-friendly layout is in a website's success; virtually any experienced web developer will always recommend creating a mobile or responsive version of a site to maximize its potential audience. We also know that a mobile-friendly site version is one of the many, many factors that Google takes into account when sorting its search rankings, with sites that are not optimized for all major devices being unfavorably compared to those that are already mobile-equipped. Really though, the biggest incentive for investing in a mobile or responsive version of your site is the potential audience; when more users are on mobiles than on desktop, not doing so is simply removing a large chunk of your audience. For areas such as India or Japan the majority of internet access is via mobile, but even in places that still have a high amount of desktop browsers such as Europe you'll still find many who will split their browsing between devices; by not having a mobile layout you're risking losing page views from users in transit as well as pure mobile browsers.

So, that you should have a mobile-friendly version of your site is a no-brainer, but doing so does throw up a range of new potential issues that a purely desktop-focused site wouldn't have to worry about. With multiple devices, operating and browsers available, there will be times when a particular site issue only affects the mobile site or particular mobile browsers; this can be a problem if you don't have a test device handy; if an issue is only being experienced by iPhone users in the Safari browser, then if you don't have that particular device to hand it can make troubleshooting a challenge. Thankfully, there are a multitude of tools, emulators and other solutions available to help you test and diagnose mobile issues, which we'll be looking at in this post.

IOS Simulator

If you are using the OS X operating system on an Apple computer, then you may download a free Xcode app. Xcode is a packet of applications which provides developers with a unified workflow for user interface design, coding, testing, and debugging. This might seem useless for testing a mobile site, but one of the included apps is a Simulator, which will create a testing environment that emulates the functionality of a range of Apple devices, from iPhones to iPads; with it, app or site functionality can be tested without a device to hand, or just to avoid the rigmarole of transferring data between tests. To launch a Simulator instance, click on the Xcode icon within the Dock and select Open Developer Tool > Simulator. If you'd rather open only the Simulator directly without going through the Xcode interface you'll need to navigate to Applications / Xcode / Content / Developer / Applications / to do so; if you're intending to use the Simulator in this way regularly then it's a good idea to copy the icon to your dock to create a shortcut instead of fiddling around in your application folders every time.

IOS Simulator
IOS Simulator.

Now we've got the Simulator open we can start testing our site to see how it works on iOS devices. From the top menu navigate to Hardware → Device and select a device such as iPhone, iPad or iPad Air; this will configure the simulator to emulate the chosen device so you can see how your site performs; we can also simulate gestures to test handheld-specific features, like shaking or rotating the screen. There are also other useful options such as a "Slow animation" feature or "Color Off Screen Rendered", which adds a yellow overlay onto content that will not appear in the mobile viewport, which allows for fine-tuning of content layouts. It's great for testing, but what if we want to get our hands dirty and start debugging the source code of the mobile Safari website? It can be done, but we'll need to put a bit more effort in via the following steps:

  • Make sure that your Safari desktop browser, Xcode simulator and OSX are up-to-date (Lion 10.74 or higher is required)
  • Enable Developer Tools in your iOS simulator. This is very easy to do, just open the simulator, navigate to Settings → Safari → Advanced in the main menu and make sure that the "Web Inspector" option is enabled:
    Enable Web Inspector
    Enable Web Inspector.
  • Next we need to enable Developer Tools in your desktop version of the Safari; If you can't see "Develop" in the menu bar then you'll need to add it by navigating to Safari → Preferences → Advanced in the menu and clicking on the "Show develop menu in menu bar" checkbox.
  • Now you can open your website in the simulator, then switch to your desktop version of Safari and click on Develop → Simulator, which will tell the browser to pull its viewport from the simulator; you should now see your website as displayed in the simulator in your browser, so you can use all your usual Safari tools for debugging!
    Debugging with IOS simulator
    Debugging with IOS simulator.

Mobile devices and the Chrome browser

Almost 70% of all websites are browsed by visitors using the Chrome browser, so it's inevitable that testing and debugging websites on the mobile version of Chrome will be a major part of running a popular site. In this case, basic debugging is extremely simple thanks to the extensive features of Chrome Dev Tools. In fact, Chrome Dev Tools is probably the website tool I personally use the most! The last major release of Developer Tools also included a brand new feature that simplifies the testing process; it now allows for users to switch into Device mode by clicking the "Toggle Device Mode" icon at the top-left of the Developer Tools taskbar:

Debugging and testing with Chrome tools
Debugging and testing with Chrome tools.

With Device Mode activated we can now select the device what we want to test or debug; if the device is not listed, we can also set the custom screen width and height or just drag the edges of the viewport to our desired height and width ratio.

We also have some other great tools at our disposal which will help us to build a more welcoming site for users with variable internet services; with Dev Tools we can simulate network speeds and conditions e.g. we can choose to simulate a GPRS or slow 3G connection to get an idea of the user experience our site provides under sub-optimal conditions.

Another great feature for building an effective mobile site is Media Query Inspect - by clicking the "Media queries" icon in the upper left corner of the viewport you can easily access and inspect the media queries on the current page. Dev tools can detect all media queries in your stylesheets and display them as colored bars in the top ruler. You can also right-click a bar to view where the media query is defined in CSS and jump directly to the definition in the source code.

Media Queries with Chrome device mode
Media Queries with Chrome device mode

You can also emulate the touch screen and its associated gestures; to access the sensor controls simply open the DevTools emulation drawer by clicking the More Overrides option (represented by a three dots icon) in the top right corner of the browser viewport. Then, select Sensors in the emulation drawer.

Chrome users also have alternative methods available such as remote debugging on Android via Chrome. You'll need to be running Chrome 32 or later on your desktop machine for this to work, and you're going to be connecting your Android-powered device directly to your desktop so you'll need a USB cable, plus Chrome needs to be installed on your Android device too, for obvious reasons. There is one peculiarity in this regard though; in order to use remote debugging your desktop version of Chrome must be newer than the version currently installed on your Android device; if you're the kind of person who likes to keep their mobile browser at the cutting edge then you may find that you'll need to have Chrome Canary (the test build of Chrome where new features are tested and implemented) installed on your development machine to give you that extra step over the mobile version.

Setting up Chrome Remote debugging

Once you've got all the pieces needed getting remote debugging up and running takes no time at all:

  1. On your Android device, go to your Settings → Developer Options section of the settings screen. If you can't see the developer options then you'll need to do something that might seem a bit strange; select Settings → About Phone and then tap "Build number" seven times (yes, really!).
  2. In the Developer Options make sure that the "USB Debugging" option is checked.
  3. Connect your Android device to your development machine using a USB cable.
  4. On your dekstop version of Chrome, navigate to chrome://inspect (literally enter the text into the address bar and hit enter), and make sure that the Discover USB Devices option is enabled. Check your device now, as there may be an alert prompting you for permission to allow USB debugging from your computer, which you'll need to agree to.
  5. Now on your computer the Chrome inspect page should display the connected device with any open tabs taken from your Android Chrome browser. To start debugging, click inspect below the browser tab you want to debug.
Debugging Android device with Chrome
Debugging real Android device with Chrome

The similar remote debugging may be done with the FireFox browser for Android, more information may be found in the Mozilla Documentation .

Android emulator

Android also provides an emulator application, much like the simulator included with Xcode for OS X. Installing the emulator takes just a moment:

  1. Download the Android SDK, which you can find on the Android developer site .
  2. Install Android OS; you'll need at least one version of the Android platform. To install, run the android command placed in the tools directory of the SDK (you can do this via Terminal on or the Windows Command Prompt). The window should pop up and you can make a selection from the available packages.
  3. While still in the Android tool, click on Virtual Devices on the left and click "new". Here you can set some useful options for debugging, such as hardware, SD card etc... Next click the "Create AVD" button, and your new device should be added to the list of Android Virtual Devices.
  4. You may now select the created device, click "Start" button and the emulator will start running.


BrowserStack is a cross-browser testing tool. With it you can test your website across browsers on multiple operating systems and mobile devices without individual virtual machines, devices or emulators. BrowserStack also offers remote testing on physical devices, so if you find yourself needing to test your website performance on many devices it can be a helpful time saver. There's a cost for using this tool, but you can use a Free Trial of the service to give it a test run to see exactly how it works and whether it's right for your needs.

BrowserStack quick launch
BrowserStack Quick Launch

Do you know other great tools for inpecting or debugging mobile devices? Let us know in the comments!

This article was updated on November 3, 2019

Bob Mitro

Bob is a co-founder of the Publii project and a web designer and front-end web developer with over thirteen years of professional experience in the design industry.