pwas-the-future-of-the-mobile-web technology

Progressive
Web
Apps:
the
future
of
the
mobile
web
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— Foreword, 3
— Great Mobile Expectations, 4
by Jenny Gove
Mobile Usage, 5
User Research: Mobile Web and Native Apps, 7
The Best of Both: Progressive Web Apps, 11
— What are Progressive Web Apps, 12
by Chris Heilmann
A Brief History of Software Delivery, 13
A Current Need Fulfilled, 14
Progressive Web Apps to the Rescue, 15
The Technology Stack, 17
— How to Build Progressive Web Apps, 19
by Sarah Clark & Sam Dutton
— PWA Design Considerations, 21
by Mustafa Kurtuldu & Ryan Warrender
Designing For a Shift in User Expectations, 22
Designing For Different States, 23
Use Metaphors That Convey Meaning, 26
Design For All Your Users, 27
Post PWA Launch, 30
— Case Studies, 32
Lancôme, 33
trivago, 34
BMW, 35
Nikkei, 36
Pinterest, 37
— Afterword, 39
— Resources: Checklist, Tools, Useful Links, 40
Checklist, 41
Resources, 41
Tools, 41
Mobile Excellence, 42
Videos, 43
— Content

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— Foreword
In recent years, mobile usage has risen to the point where people now spend twice as
much time on mobile devices as they do on desktop, and in many countries mobiles are
the only device they use. This isn’t news: you’ll have seen the same trends in your site
analytics.
With this boom in usage comes expectation. Users demand consistently great experien-
ces on both native apps and mobile websites, and expect to switch seamlessly between
them depending on their requirements. Developers and designers now need to build
and maintain native apps for multiple operating systems (OS) alongside a mobile web-
site - a process that requires a substantial amount of time and effort. And when - as
often happens - the experience delivered by a company’s website and their native app
is worlds apart, users end up frustrated. Surely there must be a better way?
Well, now there is: Progressive Web Apps. The concept of a Progressive Web App (PWA)
was first introduced in 2015. PWAs are sites that employ modern technology to deliver
native app-like experiences on the web. This e-book explores todays mobile web expe-
riences and why PWAs provide revolutionary solutions to improving experiences on the
mobile web. We’ll look at what we really mean by a ‘PWA’, the unique features they offer
users, how to build one, and how to assess the results.

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Progressive
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Great Mobile
Expectations,
Mobile Usage
Consumers expect mobile to meet their needs for
everyday tasks such as shopping, communications,
and entertainment, and it is the job of designers
and developers to provide experiences that live up
to these demands. To do this, mobile experiences
need to be fast, installable, reliable and engaging,
and should operate in a secure and accessible en-
vironment.
Over the last few years there has been a big shift in
the digital platforms users occupy, with mobile de-
vices now considerably more commonplace than
desktops. ComScore1
reports that in the majority
of countries, mobile users spend more than twice
the digital minutes of desktop users. But desktop is
still important and continues to contribute 50% or
more digital time for retail, portals, business and fi-
nance, travel, autos, and education. Mobile audien-
ces have larger reach for some of these categories
however2
, and consumers will often switch to the
platform that best supports their needs.

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In addition to this, populations new to digital, coming
online for the first time, have contributed to a gradual
shift towards mobile-only internet access. Consumers in
Asia Pacific (APAC), in countries like India and Indonesia3
,
are encountering the web via mobile device only. And
Millennials use mobile devices more than other genera-
tions, although adoption is growing significantly among
older generations as well4
.
The vast majority of time on mobile is spent in native
apps5
, with ComScore reporting that 80% of all mobile
minutes in all markets are spent in native apps, versus
20% in mobile web. However, a very limited number of
native apps account for that time - primarily social ne-
tworking, music, games, and entertainment. And in terms
of reach, the mobile web tends to capture larger au-
diences: according to ComScore, the mobile web has on
average 2.2X more unique visitors per month than native
apps6
.
1.
ComScore: Global Digital Future in Focus,
2018 International Edition
2.
ComScore: The Global Mobile Report, 2017
3.
ComScore: Global Digital Future in Focus,
2018 International Edition
4.
Pew Research Center: Millennials stand out
for their technology use; but older generation-
salso embrace digital life
5.
ComScore: The Global Mobile Report, 2017
6.
ComScore: 2017 Mobile App Report

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User Research: Mobile Web and
Native Apps
The importance of a mobile web presence cannot
be overstated, with consumers frequently turning to
mobile websites to research and explore their options.
In fact, mobile websites are the primary method of dis-
covery, as this participant in a Google user research
study explained:
“If you’re, like, ‘I know I’m kind of looking for this’,
it’s probably easier to go to a mobile website and
search… I have this sense that there are more
products and content available on a mobile web-
site versus an app.”
Because they are judged to have the best reach, users
often look for information across a variety of mobile
websites using Search; a helpful way to explore alterna-
tive options, prices, and reviews.
Tip: Mobile websites can reap the be-
nefits of search rank and SEO for dis-
coverability (see Google’s Search
Engine Optimization Starter Guide).
Although consumers turn to mobile websites for explo-
ration and discovery, they generally perceive native apps
to have greater ease of use. Native apps are created
mobile-first from the start and this is an approach that
tends to lead to better design around user goals and a
smoother experience. Though some mobile websites
have been designed very well from the outset and are
more usable, and less advanced websites may feature
less frequently in search results, users still encounter
many websites that provide a poor experience. Cumula-
tive exposure to these may lead users to conclude that
native apps do a better job:
“[The apps I like] are really designed to be really
user friendly and easy. You can get in, get out, do
[your] thing.”
Tip: Use Google’s Material Design Gui-
delines and components to create a
great experience, developing a consis-

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Material Foundation. The color system.
Credits: Material.io
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tent look and feel across mobile web-
sites and in native apps.
As native apps are often designed for specific tasks, pur-
pose-built to deliver only the most important features,
they can also feel more streamlined and goal-oriented
than mobile websites:
“In my experience, apps have less features than
a website does. So they’re very streamlined, and
tailored towards the end result [...]. There's less
features on an app, because the goal is to get you
there as quickly as possible.”
Native apps often contain features that allow users to
store payment details, account information, or settings
and preferences, making purchasing an easier and quic-
ker experience. Because of this, they can be perceived
as more personalized:
“[An app is] designed to be around you. It’s got
your order history right there, easily accessible.
It’s probably got some sort of personalization set-
tings [...].”
Tip: Reduce the burden on consumers by
streamlining the UI for login and pay-
ment. Deliver speedier sign-in expe-
riences for your mobile website (one
tap sign-up and auto sign-in on web-
sites) or native android app (using
Google sign-in). And use Google Pay
for a seamless payment experience on
native apps and mobile websites.
Native apps are also considered easier to find and
access:
“Because it’s there on the screen on my phone,
and I know what it looks like and it’s easy to
press... A site, unless I bookmark it, which someti-
mes I forget to do, I’ll have to kind of remember or
go to Google and kind of start typing it and see...”
Tip: Implement progressive web app te-
chnologies that allow users to access
your website from their homescreen -
just like they do with native apps (see
Add to homescreen)
.

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Consumers also feel that native apps give them a faster
initial experience:
“I would say the apps almost always work faster
than mobile web.”
Tip: Use AMP (Accelerated Mobile
Pages) to create super fast landing
pages for websites.
On the other hand, native apps take up significant sto-
rage space on the device, meaning users may only install
apps they plan to use frequently:
“I tend to not download apps unless I decide that
I really could use them a lot, more than once, with
few small exceptions. I don't have a lot of apps
that I don't access very much. So if it's a one-
off thing, I will most likely just go to the website,
look for the information, then I move on. The app
is something that I will use often, over and over
again.”
Both mobile websites and native apps must strive to
keep their experiences frustration-free for users. Ad-
verts that interfere with the user experience, or fre-
quent, irrelevant notifications that get in the way of
consumers’ goals, can all contribute to poor experien-
ces. Users are likely to abandon mobile websites with an-
noying ads, and turn off notifications completely if they
become intrusive:
“I don't want to be scrolling past the ads, or the
ads take longer to load, and it's making my phone
less functional. I don't want to spend time on
that.”
“I find if you have notifications for everything,
then nothing is important.”
Tip: Deliver a better ad experience
using the guidance provided by the Coa-
lition for Better Ads, and apply the
Material Design guidelines to create and
schedule appropriate notifications for
your users (see: Android notifications).

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The reality is that users will switch platforms as required
in order to find the information or service they want. A
recent study found that 46% of mobile shopping ses-
sions include at least one transition between mobile
website and native app. The experience therefore needs
to be high quality, fast, reliable, secure, and engaging
across all platforms that you support. Additionally, some
native apps benefit from having mobile web integra-
ted into them, and technologies like Trusted Web Ac-
tivities available for Android) allow you to achieve this
seamlessly, delivering an experience that has a consis-
tent look and feel.
Users believe, in general, that native apps provide a clea-
ner and smoother experience, are more tailored to indi-
viduals, and are faster to load and use. However, mobile
websites are the first port of call for exploring a topic, ser-
vice or product, and for seeking specific information. In
addition, they don’t require downloading; and with advan-
ces in technology, mobile websites can be as speedy and
usable as native apps. Taking advantage of these new te-
chnologies should enable you to deliver great experiences
on the web - meeting the user’s every need, every time.
The Best of Both: Progressive
Web Apps
Progressive Web Apps (PWA) are websites that use
modern web technologies to create mobile web expe-
riences that are closer to those delivered by native apps.
Via a link on the homescreen, users can enjoy features
that were previously challenging on the web: accessing
content offline, receiving notifications from preferred
brands, adding favorites to the homescreen. PWAs help
improve user engagement and enable seamless conver-
sions - whether for e-commerce, productivity, publi-
shing, games, or media.
While mobile has been one of the main drivers of the te-
chnology, desktop is a growing market. PWAs enable fric-
tionless journeys for mobile, tablet, and desktop users, and
so regardless of the platform, they have a key role to play.
Let’s look in more depth at what a PWA is, and how they
work.
7. Mobile web through the users’ eyes: How
Progressive Web Apps can address UX Issues.
8 ThinkwithGoogle: 3 benefits to merging your
mobile site and app teams

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What are
Progressive Web
Apps,

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Progressive Web Apps are an exciting and pragmatic way
to deliver the best software functionality to users. But
before going into the details of the ‘how’, let's talk quic-
kly about the ‘why’.
A Brief History of Software
Delivery
Historically, software was delivered as applications. You
bought it on floppy disks, CDs, or memory sticks, insta-
lled it and used it. This cumbersome process meant that
software was rarely upgraded. The cost of creating phy-
sical products and mailing them out was high, and when
an error cropped up there was no easy fix.
But the web changed things. Instead of ordering phy-
sical media, you simply downloaded and installed the
software you needed. As browsers and technology de-
veloped, even that process was simplified: instead of
downloading and installing, you typed in a URL or clicked
on a link. Finally, we had proper software-on-demand.
The advent of smartphones pushed things forward again.
The software-in-a-browser format wasn’t ideal for the
What are
Progressive Web
Apps,

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form factor; typing URLs on a mobile device was tricky.
The interfaces we built with web technologies (HTML, CSS,
and JavaScript) were often optimized for big screens and
mouse interactions. But the main problem was that they
required the user to be online - and mobile connectivity
tended to be less reliable than a wired connection on a
desktop or laptop.
Native apps on iOS and Android delivered what mobile
websites couldn't: the ability to work offline, and an ex-
perience optimized to the form factor of a smartphone.
So, we started offering software and media through app
stores.
A Current Need Fulfilled
But it has become clear that this is not a perfect solu-
tion either. Distributing software to end users via a store
is convenient for developers and it feels more secure, as
a curated store can filter malicious software. But it also
means building several versions of native apps for different
operating systems and form factors, which not everyone
can afford. Developers are reliant on stores to publish and
distribute an app, and may need to share the profits with
them. The store provider might impose a review period
on new releases - and some users won’t be happy to re-
peatedly update big apps - so it’s harder to publish new
versions.
Delivering our solutions in closed stores and in a native
format also involves a lot of assumptions. App stores don’t
always support legacy devices, so they rely on users to
have a certain operating system or the newest version of
a device. Users need enough storage available on their
device, and of course, native apps tend to involve a lot of
data, so they require fast, unlimited connections to down-
load and update. Users are expected to have a credit card
to make purchases.
But if we look to markets with the most new users we can
see just how unrealistic even these basic assumptions are.
It is therefore vital to find a way to marry the immediacy
and low entry barrier of the web with the form-factor op-
timization and functionality of native apps.

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Progressive Web Apps to the
Rescue
Enter Progressive Web Apps. As the name suggests,
PWAs are applications that use web technologies to give
us the best of both the web and native environments.
They are delivered in a progressive way, which means we
don't need to build them in different formats: we deliver
a basic solution as a website and add extra functionality
as we go.
Progressive enhancement has been used to deliver web
content for some time - because it makes sense. Instead
of expecting users to have a certain browser or particu-
lar hardware, we aim to deliver something that works for
everybody. More up-to-date systems may enable newer
and more complex features, but the essential functions
should just work without the user having to worry.
PWAs are delivered via a link in an email, a chat, search
result, a beacon, a QR code, or from an ad. The PWA
provides a suitable interface for the device and form
factor, is immediately available, and the user can try

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before buying. Whilst a user interacts with the PWA, we
can check the capabilities of their device and load more
data in the background. We can also offer increased
functionality further down the line - offline usage, noti-
fications when new data is available, and various other
conveniences.
Initially, PWA descriptions seemed complex and daunting
for developers. A PWA needed to be:
• Progressive - more functionality becoming available
on subsequent visits, depending on the capabilities
of the consumption device.
• Responsive - an interface that catered to the envi-
ronment, offering smooth and immediate interac-
tion.
• Network independent - the PWA functions both
offline and online as well as on flaky connections.
• Native App-like - a PWA must work like any other
app: fullscreen and in its own context, with no need
for a browser.
• Fresh - updates happen automatically with no
long-winded installation process

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• Safe - data delivered over secure channels.
• Discoverable - a PWA is available on the web as well
as in app stores.
• Re-engageable - notifications don’t require the
PWA to be continuously open.
• Installable - the PWA displays alongside all the other
apps (start menu, icon on homescreen, app search
result on device...).
• Linkable - accessed via a simple delivery mecha-
nism, such as a link.
As PWAs continued to evolve, we began to develop a
more digestable definition of what makes a good PWA.
One of the frameworks you might have seen is FIRE: Fast,
Installable, Reliable and Engaging.
And refining it down to three characteristics PWAs
should be:
• Fast - the first contact with a PWA interface is an
immediate, responsive, and enjoyable experience.
• Installable - a PWA installs like any other native app,
showing on your desktop or homescreen rather
than requiring a browser.
• Engaging - the PWA follows the best practices for
high-quality UX & UI and works irrespective of ne-
twork state or device capability. The experience
may be limited, but there’s never an empty screen
telling the user to go online or upgrade.
The Technology Stack
Achieving this required a lot of new functionality - func-
tionality which is now available on all browsers and ope-
rating systems, and is based on consensus amongst the
different companies who maintain them. This makes de-
veloping a PWA more achievable than ever, and because
the PWA technology stack is progressive, it can be as
simple as running a PWA as a website in a browser tab.
But you can also do more than this, using two new web
standards to increase functionality.
The first step is to build a website that will be your appli-
cation. It should follow responsive web design principles
and be as small as possible: you want the first experience
to be fast and smooth. Because PWAs are written using
HTML, CSS, and JavaScript, like any other website, there
is no need to install a development environment.

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The second step is to create a web manifest - a JSON
file that describes your PWA. It will include the PWA’s
name; whether it opens in landscape or portrait; what
access it needs to the device; its description, screens-
hots, and icons. The web manifest tells capable browsers
and devices that this is a PWA, and essentially defines the
user interface. When a user clicks on a link to a PWA, the
manifest will trigger an opportunity to install the applica-
tion for later use.
The third step is to set up a Service Worker, a JavaS-
cript solution that runs in the background when a user
accesses a PWA. It allows you to define what data to
store on the device and what to reload from the web
when the user is online again. It also lets you decide
when and how to update the application, and what noti-
fications the user gets.
PWAs are a natural evolution of how we distribute and
consume software. Because they are based on web
technologies, they are independent of any operating
system or development environment. A responsive, en-
gaging, and exciting website gives you the fast founda-
tion - delivering speed and immediacy. The manifest file
makes the PWA installable - telling a user what they’re
getting and how to access it; and Service Workers make
it reliable and engaging - a solution that adapts to ne-
twork changes and keeps the user notified.

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How to Build
Progressive
Web Apps,

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The goal of PWAs is to build the core of a responsive
website and add technologies incrementally to enhance
the experience. That’s what makes them progressive! To
help developers level up their skills and understand the
new design mindset, Google has created a course for
Progressive Web Apps Training, available at developers.
google.com/web/ilt/pwa
This course is aimed at:
• Beginning-to-intermediate web developers.
• Web developers who are comfortable using HTML,
CSS, and have modest capability with JavaScript.
• Developers who want to build web experiences that
work for everyone.
To see how the course could help you, watch the intro
video here.
How to Build
Progressive
Web Apps,

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Designing For a Shift in User
Expectations
Progressive Web Apps will inevitably drive a shift in
user expectations. Users may be accustomed to ‘no
network’ pages like the Chrome T-Rex, but the moment
you remove a browser’s UI, they will assume a superior
level of functionality. Many native apps - news apps, for
instance - work regardless of network connection, so
previously downloaded content can still be browsed.
It is critical that PWAs meet the same standards,
otherwise the experience will feel broken.
PWA Design
Considerations,

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How do we begin to devise an experience for a PWA?
There are a few fundamental considerations:
• Responsiveness - Ensure that a PWA will work on all
devices across mobile, tablet, and desktop.
• Think about UI - Mock up your designs with and wi-
thout the browser UI to help uncover any potential
layout issues.
• Different states - Remember to design for diffe-
rent states: online, offline, flaky network, content
loading, and content failing to load.
• App icon - Consider each different OS and provide
an icon for each.
• Asking permission - Think about when you’ll
prompt the user to add the PWA to the homes-
creen. Too soon may seem pushy; too late and they
might not bother.
• Asking for location data - Remember to do this in
context so the user can see its value.
Designing For Different States
When first approaching PWAs we tend to think about
states as being binary: offline or online. The reality is
more fluid: offline may only last a few seconds, and
there may be a transition period known as Li-Fi, where
the device believes there is a network but that network
lags.
There are multiple reasons why a network might fail,
including:
• Poor network coverage.
• Power outages or bad weather conditions.
• “Dead zones” where buildings or train tunnels block
the network connection.
• Time boxed internet connection (for example in an
airport or hotel).
• Cultural practices that require limited or no inter-
net access at specific times or days.

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Occupying the user’s time
According to an anecdotal account, Houston Airport
found an ingenious way to deal with long waiting times
for baggage collection. To solve the issue they switched
arrival gates for the problematic flights. Customers had
further to walk, but they spent less time waiting around,
which resulted in fewer complaints.
Similarly, an ‘offline state’ needs more than just error
messages or progress bars. Clever ways to engage a user
while they wait for the network to come back (which
might only take a few seconds) can make all the diffe-
rence to how smooth and enjoyable an experience feels.
For example trivago, the price comparison site, now lets
you play a game if the network goes down; and they’ve
found that 67% of users whose internet connection is in-
terrupted still come back to browse.
The key thing to remember is that it’s vital to replace a
loading spinner with something relevant, rather than just
a gray box. Skeleton screens are a neat way to show the
user that something is coming, and patterns like the one
On the left trivago indicates an offline status; on the right, a
game launches if the user tries to navigate to sections that
require internet access.

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below can hack the user’s perception, convincing them
that pages are loading faster. But as soon as the content
is available, we need to see it: displaying critical con-
tent first ensures that the user sees progress. Youtube,
for instance, always makes sure the video loads first;
everything else is secondary:
Inform the user of changes
You might need to notify a user for all sorts of reasons:
changes in network connection, updates to the site or
the content, price changes in an e-commerce store.
Take a look at the examples below:
Use Metaphors That Convey
Meaning
PWA experiences are relatively new, so it’s important
that the terminology and imagery informs rather than
confuses the user. Icons alone can be problematic, me-
aning different things to different people. For example,
a floppy disc symbol for ‘save’ might make sense to an
On the left, Chrome status notifies the user to get the latest
version; on the right, Material Money informs the user when the
currency rates need updating.

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older generation but mean nothing to younger people.
Likewise, the 'hamburger' menu icon has been known to
confuse users.
Consider how to demonstrate the action you are trying
to convey, rather than presenting the user with an abs-
tract concept. For instance, if your apps require the user
to choose which data needs to be synced in case of flaky
networks, asking them to save or download data would
be a good prompt.
Example: Material Design Icons that convey meaning.
Design For All Your Users
Developing a PWA demonstrates that a company is prio-
ritizing their users’ time, delivering faster loads and more
engaging functionality. Progressive PWA features should
therefore accentuate the experience, not distract from
it. Before deciding which features to add, ask yourself
why a user is coming to your site: a well-designed PWA
should make it easier for users to complete their goals.
Below are the top PWA UX best practices:
Less is More - Online, people tend to scan rather than
reading in detail, and prefer not to sift through too much
information. If an element on your site has a low Click
Through Rate (CTR), it’s possible your users can’t see its
value or relevance. To address this, prioritize the primary
Call-To-Action (CTA) and remove elements with low en-
gagement, which in turn will reduce your page weight.
Have a clear and memorable value proposition in a pro-
minent position. Tip: Avoid automatic sliders.
Be Consistent - Ensure fonts, media, and images have
a consistent look and feel and contribute to the overall

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brand strategy. Tip: Retrieve custom fonts on subse-
quent loads and use device fonts whenever possible.
Perceived performance - Let the user know that they’re
making progress by loading skeleton screens and using
transition animations. This should help reduce bounce
rate and encourage users to wait to continue their jour-
ney (or return if a connection is interrupted).
Navigation - Keep the navigation simple, fast, and at the
bottom of the viewport, making it easier for users to find
their way around and return home when needed.
Reduce Friction - Make procedures as smooth as possible.
Users tend to have very little patience when tasked with
completing forms and finalizing the checkout process.
In fact, the most common reason for a user abandoning
a cart while shopping on mobile is "problems entering
personal details” (see chart below). Tip: use express
checkout solutions like Autofill, Web Payments and One-
tap sign-in to collate everything a user needs at chec-
kout, while keeping information safe and secure.
Mcommerce Issues that Resulted in Cart Abandonment According
to Digital Buyers in Germany, the UK and US, Nov 2017
% of respondent
Source: Addressy "Fixing Failed Deliveries: Improving Data Quality in Retail"
conducted by Loudhouse, Dec 5 , 2017
8%
27%
33%
35%
Other
Problems entering my order accurately
Loss of connection
Screen not big enough to see what I was buying
Problems entering personal details 39%

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Push Notifications - Push notifications can increase user
engagement, but they carry more impact if delivered at
the right time. Don’t force the user to opt in on the ho-
mepage - imagine walking into a store and immediately
being asked by an assistant if you want to be kept up-
dated in future. But if you’re trying something on, and
someone politely asks if you’d like to know when it be-
comes available in the right size, you’re far more likely
to say yes. When push notifications add real value, users
are far more likely to opt in.
Accessibility - When we say a site is accessible, we mean
that the content is available to all, and can be operated
by absolutely anybody. Web Content Accessibility Guide-
lines (WCAG) 2.0 is a set of best practices put together
by experts to address exactly what "accessibility" means,
and how to deliver it.
WCAG is organized around four principles, often refe-
rred to as POUR:
• Perceivable: Can users perceive the content? Just
because something is perceivable with one sense,
such as sight, that doesn't mean that all users can
experience it.

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• Operable: Can users navigate the content? A hover
interaction, for instance, cannot be operated by so-
meone who can't use a mouse or touch screen.
• Understandable: Can users understand the con-
tent? Is the interface clear, and consistent enough
to avoid confusion?
• Robust: Can the content be consumed by a wide
variety of user agents (browsers)? Does it work with
assistive technology?
Post PWA Launch
Congratulations on taking advantage of this revolutionary
technology and upgrading your systems to a best-in-
class web experience.
Once a PWA is live, it’s important to track user engage-
ment, monitor impact, and iterate the UX as needed.
There are several tools and techniques available to help
you with this:
Performance - After launching a PWA it is common to
see improvements in site speed. Monitor First Con-
tentful Paint (FCP), Time to Interactive (TTI), and Speed
Index, continually auditing your PWA experience with
Lighthouse, Chrome User Experience Report, and Web-
PageTest.org. Test the PWA experience across different
network conditions and on various hardware devices.
New Acquisitions - Check bounce rate to see if impro-
ved performance, transition animations, and skeleton
screens are actually keeping the user on the page.
User Engagement - Confirm that PWA features like Add
to Homescreen and Web Push are improving user enga-
gement. For Add to Homescreen, use metrics like time
on site and repeat visits to compare those who launch
from the homescreen vs. those who come through the
browser. For Web Push, track CTR for different notifi-
cations and again, use time on site and repeat visits to
compare those who received notifications vs. those that
did not. The engagement metrics for any feature should
demonstrate a trend towards a higher conversion rate
overall.

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Conversions - For most organizations, increasing con-
versions is one of the main reasons they’ve invested in
building a PWA - so they’ll want to know it’s working.
Retailers can track conversions by monitoring Average
Order Value (AOV) and the exit rate on the page where
the checkout funnel begins. Lead generation compa-
nies should focus on CTR of the primary Call-To-Action
button and the lead to close ratio (successful sales /
number of leads * 100). Travel sites can monitor return
sessions (customer retention) and channel-specific tra-
ffic (i.e. are social shares increasing?).

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Case

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Lancôme
In 2016, Lancôme saw mobile traffic eclipse desktop
for the first time. But despite a growing number of
mobile site visitors, mobile conversion rate was only
15%, compared to 38% on desktop. Lancôme conside-
red building an app, but decided that their shoppers
wouldn’t return to an e-commerce app weekly, let
alone daily. So instead they looked to PWA techno-
logies for a web solution that provided an immersive,
app-like experience.
With the new PWA, Time to Interactive fell by 84%, with
a corresponding 15% decrease in bounce rates. Lan-
côme saw their mobile sessions rise by more than 50%,
and conversions increase by 17%. On Android devices,
they took advantage of re-engagement strategies like
push notifications, which became very popular: Over
18,000 shoppers have signed up for alerts since the
PWA launched in October 2016.
READ THE FULL CASE STUDY
84%
decrease in
mobile load
time.
17%
increase in
conversions.
50%
increase in
mobile
sessions.

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150%
Increase in engagement
for users who add to
homescreen.
50%
increase in mobile
sessions.
trivago
As one of the world’s leading hotel search engines, tri-
vago has a history of innovation. They are always on the
lookout for new disruptive solutions, so developing a
PWA was a natural next step. Currently their PWA-evol-
ved website is available in 33 languages, across 55
countries, and they report that features like offline
access, push notifications and add to homescreen are
particularly valuable to their users:
“Just as we now no longer accept websites constantly
reloading while we browse for fresh content, mobile
users who experience the seamlessness of PWAs will
quickly come to expect sites to just work, regardless of
flaky wifi or poor mobile reception,” says Tom Dwyer,
Project Lead for PWA and Front-End Developer at tri-
vago.

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BMW
Since 1916, BMW has epitomized quality, style, innova-
tion, and performance. So, when its digital team deci-
ded to refresh BMW.com, they had clear expectations
as to how it should work, look, and feel. Their agency,
Jung von Matt, completely relaunched the site using
a PWA shell and all-AMP content. Development took
about six months and launched in fall 2017, dramatica-
lly increasing performance with colorful, informative,
fast-loading article pages.
“Right from the start, our goal was to attract new car
enthusiasts with highly-engaging content—and in a
way that tangibly reflected our vehicles. To do that,
we needed the brand’s new digital home to become a
data-driven content platform, built around high-per-
formance technologies like AMP and PWA,” says Joerg
Poggenpohl, Global Head of Digital Marketing BMW.
3-4x
faster load times.
30%
higher click-
through rate to
national sites.
26%
more mobile
users.

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Nikkei
With a publishing history of more than 140 years, Nikkei
is one of the most authoritative media businesses in
Japan. Along with their traditional print newspaper,
they have over 450 million monthly visits to their digital
properties. To provide a better user experience and
accelerate their business on the web, Nikkei success-
fully launched a Progressive Web App (PWA) in Novem-
ber 2017. They’re now seeing amazing results from the
new platform.
Their Lighthouse score soared from 23 to 82. Their
time-to-interactive measurement improved by 14 se-
conds. Organic traffic, speed, conversion rate, and
active daily users all rose as well.
2x
faster load
times.
2.3x
organic traffic.
58%
better
conversion
rate.

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103%
increase in weekly
active users on
mobile web.
296%
increase in
session length.
26%
increase in new
sign ups.
Pinterest
Pinterest historically invested a lot in its iOS and An-
droid apps while the mobile web experience was far
from perfect. One year ago (July, 2017) they have brou-
ght a team together to rewrite their mobile website
from scratch as a PWA. This was the culmination of se-
veral years of conversation, months of metrics investi-
gation and one large hypothesis: mobile web can be as
good as a native app. And they’ve created a true PWA
that supports an app shell, add to homescreen, push
notifications, asset caching but also right-to-left lan-
guages and even a “night mode”.
And they’ve seen great results across the board.
Weekly active users on mobile web have increased
103% year-over-year overall, with a 156% increase
in Brazil and 312% increase in India - emerging mo-
bile-first markets. On the engagement side, session
length increased by 296%, the number of Pins seen
increased by 401% and people were 295% more likely
to save a Pin to a board. Logins increased by 370%
and new signups increased by 843% year-over-year.
Since they’ve shipped the new experience, mobile web has
become the top platform for new signups. And in less than 6
months since fully shipping they already had 800 thousand
weekly users using our PWA like a native app (from their ho-
mescreen).

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More case studies available at:
developers.google.com/web/showcase
& pwastats.com

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— Afterword
So there you have it: a step-by-step guide to how PWAs have evolved from existing te-
chnologies to create seamless native-app like experiences on the web, that work re-
gardless of operating system. Hopefully this guide has given you a good idea of why they
are called Progressive Web Apps, how to build and deliver one for your business, and
the best practices to employ to keep your users happy, engaged, and online.
Thanks for reading.

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Resources:

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Checklist
• Progressive Web App Checklist
Resources:
• HTTPArchive Data on PWAs
• PWA Stats by Cloud Four
• Introduction to Service Workers
• Javascript Promises: An Introduction
• Is Service Worker Ready?
• Designing a Progressive Web App icon
• Hacking user perception to make your websites
and apps feel faster
• Google Codelab for building Progressive Web Apps
• Mozilla ServiceWorker Cookbook
• Details on the support for ServiceWorkers and
WebManifest in Apple Safari/Webkit
• PWA on Windows 10
Tools
• Lighthouse an open-source, automated tool for im-
proving the quality of web experiences that can be
run against any web page, whether public or requi-
ring authentication. It has audits for performance,
accessibility, progressive web apps, and more.
• PWA Builder an open source project by Microsoft
that allows you to pre-seed a manifest from an exis-
ting URL and create a ServiceWorker for you. The
technology delivers both a PWA and fallbacks for
any instances where PWA is not supported.
• Workbox a set of libraries and Node modules that
make it easy to cache assets and allow you to take
full advantage of the various features used to build
Progressive Web Apps.

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Mobile Excellence
Getting the fundamentals of mobile sites right is critical,
to stay ahead of consumer needs it’s important to lay
the groundwork for high performing mobile experiences
now.
Awwwards.com in collaboration with Google has created
this Award for recognizing and rewarding best practices
in mobile site design. The process of obtaining a Mobile
Excellence Badge is simple and transparent. In order to
win the award you must meet the optimization criteria
established by Google and Awwwards, which you can see
here in these Guidelines.
The Mobile Excellence Award celebrates sites that puts
users first, whilst bridging great design with pure per-
formance. It recognizes hard work and aims to raise the
standards of the mobile web, allowing people to have a
superior experience anytime, anywhere.

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Videos
PWAs: Building Bridges to Mobile, Desktop, and Native
(Google I/O '18)
Progressive Web Apps (PWAs) enable fast, integrated, reliable, and engaging web
experiences. Come and learn how browser vendors are enabling developers to
use the web to build installable desktop applications and store-distributed mobile
apps, as well as how Google is launching its own PWAs at scale.
Kickstarting Your Journey to Progressive Web Apps
(Chrome Dev Summit 2017)
The web is now an even more exciting place to develop, but you may be confu-
sed by the changes and not know where to start. In this video, Ewa Gasperowicz
covers how to take a web site and turn it into to a Progressive Web App expe-
rience, discusses starting points, process, options and tools, and teaches about
caveats of PWA development and their solutions.
From Website to Progressive Web App
(GDD Europe '17)
In this video, you'll learn where to start with Progressive Web Apps, what to im-
plement, and how to prioritize PWA techniques. You'll also learn how to make the
most of 'low hanging fruit' and take advantage of small changes that can have a big
impact.
UX Research and Usability Testing:
Designer vs. Developer
In this episode, Jenny Gove explains the importance of research and usability
testing and discusses various methods and approaches such as conducting a
pilot study, identifying target users, and setting up tasks.

Special thanks to:
“Craig Adolph – EMEA mWeb Product Lead at Google for coordinating all
these authors:
Jenny Gove – Senior Staff UX Researcher at Google
Chris Heilmann – Developer Evangelist at Microsoft
Sam Dutton, Developer Advocate – Developer Advocate at Google
Sarah Clark – Program Manager, Developer Relations Infrastructure at Google
Mustafa Kurtuldu – Senior Design Advocate at Google
Ryan Warrender - Mobile UX Manager at Google
Shane Cassells - EMEA mWeb Ecosystem Lead at Google
Olga Demidova - EMEA mWeb Marketing Manager

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