What’s the Difference Between PWA & SPA


pwa spa

Among many advanced tools and methods Modern web development industry has introduced, two principally different types of digital solutions – Progressive Web Applications (PWA) and Single-Page Applications (SPA). Developers all over the world tend to choose between PWA and SPA, with both options being simple to build, fairly easy to promote in search engines, and featuring some far-seeing user capabilities.

Let’s take a detailed look at particular aspects of developing these types of web apps, meanwhile comparing their major unique features and general differences.

What is SPA & PWA?

First, let’s define the terms. 


SPA is a single-page web app that automatically loads up all the server-stored content when the main page is launched (various modules, widgets, CSS files, etc.). Basically, when a user clicks a button in such an app or launches some module or fills out an input form, only the necessary content is refreshed, with all the rest remaining as it is. 

This principle boosts the overall content loading speed, affecting the level of UX in an app most positively. As a whole, the first mentions of the SPA model appeared back in 2014 and were partially related to the sweeping outspread of HTML5 (the combination of HTML, CSS3, and JavaScript).  

There is a common misconception that SPA solutions that include a lot of features (which means more script-based files) can be slowed down in performance by their single-page nature and the need to load up all the individual files. In practice, everything’s the other way round, though. AMD API is used specifically with such apps, which manages the smooth loading of scripts and task prioritization. I.e., a single-page app loads and performs only when need be, during the direct user interaction. 

Multi-Page Apps (MPAs) are a complete polar opposite and predecessor to SPA solutions. In MPAs, for each and every page to load, a server request is sent and all the content on the page is updated. These are, usually, quite slower in performance as opposed to SPAs, hindering the development workflow also with more complex software architecture and, in particular, a huge number of dependencies. 

Some of the prominent readymade SPA solutions include such big names as Gmail, Wix, Google Maps, Meduza, and Twitter. 


As for PWAs, there is a whole set of properties such solutions can boast. In a nutshell, PWA solutions should be considered especially Reliable (an app should load up immediately on the user-side, with any Internet connection speed or even in an offline mode), Fast (data transfers between the server- and user-side should be rapid, taking 3 seconds at the most), and Engaging (a prominent level of user experience should be provided – users should want to use the app again and again). 

In order to correspond with all these requirements, developers usually employ a number of specialized tools, such as Service Worker, Web App manifest, HTTPS, App shell, Push Notifications, and others to define the list of the most proper end-product requirements. The PWA concept as a whole was first introduced in 2015. 

Find out more about the ins and outs of PWA solutions

The most renowned cases of PWAs include apps like Starbucks, Housing.com, Pinterest, Flipboard, and Soundslice.

Examples of Progressive Web Apps (PWAs)

The Main Differences Between PWA & SPA

And now, to add a good share of objectivity in our brief overview, let’s consider the main, principal differences between SPA and PWA solutions. 

How they work

As we’ve already clarified, an SPA loads up the whole software code at ones, with certain script files following if need be, during the initialization of separate page modules. Such solutions are based on HTML5 which allows, among other things, to store the user activity data in the DOM storage or browser cache. 

If we talk about the principles of the PWA performance, once the app is initiated, a Service Worker script being launched to cash the whole app wrapping. After that, as new events take place and requests are made, content for View is loaded and Service Worker enables a sleeping mode up until the next event.


SPAs support only several caching methods developers can select depending on the particular project requirements:

  • Caching in the DOM storage (either local or session-based when all the data is deleted once the session has been ended);
  • HTTP caching, which is necessary when a number of requests needs to be minimized, saving as much data as possible on the client-side;
  • There is also server-side caching that allows speeding up the app performance by loading dynamic requests directly from the cache.

In the case of PWA solutions, the caching can vary in the following manner:

  • Data caching in an autonomous performance mode;
  • Reserved caching, when a website/app reacts to user requests based on its own dedicated cache without turning to the server;
  • You can also employ backups for real-time website/app interaction.


Both SPA- and PWA-solutions are much faster in performance than solutions based on standard architectures. PWAs have an additional advantage here, however – they can perform in an autonomous, offline mode. 


It is commonly considered that SPAs are utterly susceptible to search engine promotion. Nonetheless, there may appear certain indexation troubles. To avoid them, we’d recommend using polyfill.js – JS libraries that are compatible with all the existing browsers.  

As for PWAs, there is a misconception that they are better indexed by Google search than other alternatives. This isn’t really true and there are no significant advantages PWAs might have over SPAs.

SEO & PWA: How to Optimize Progressive Web Apps for Search


In both cases – SPA and PWA – user experience is much more advanced as opposed to regular web apps or sites. Nevertheless, PWAs, with their ability to load content and Engagable features immediately, are a bit better thought-out in the question of UX than SPAs. 


SPAs and earlier-mentioned MPAs are equally susceptible to XSS, MITM, and some other types of hacker attacks. That’s why you should employ some special tools for additional protection – e.g., you can create an Angular.js-based app with the built-in XSS protection, use HTTPS protocol instead of HTTP, etc. 

If we’re talking about PWAs, go straight for HTTPS protocol by default as the increased level of security is among the pillars of successful progressive solutions. 


In the accessibility perspective, PWAs are a level above other types of solutions due to their offline interaction capacities. 

Cost of development

Last but not least, what is more affordable to implement – PWA or SPA? There aren’t many differences in terms of time expenses. Users find PWAs less cost-efficient, however, due to the scarcity of available profiled developers. 

In any case, you can always turn your SPA to PWA simply by implementing correspondence with a set of additional requirements conveniently described in the Google checklist


Summarizing the PWA vs SPA stand, as you can see, both are highly efficient options for developers and users. The ultimate choice depends on certain project requirements, purposes, and such, as well as on your capacities as the project owner or manager. 

In any case, if you are interested in building an authentic project based on PWA or SPA concepts, contact us. We’ll help you painlessly implement a project of any complexity, being in the know as to the latest IT quality and reliability standards and trends.


PWAOctober 29, 2019
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