Put in its simplest terms, a Progressive Web App (PWA) is just a web site that can function offline.

The idea is that modern web browsers like Microsoft Edge and Google Chrome now have built in enough functionality that “real” apps you would previously have downloaded and installed from the Google Play Store or Apple App Store are no longer necessary for many tasks.

what is a progressive web app pwa

A simple example of this might be an airplane flight arrival / departure schedule.  When you are connected to the internet those pages must automatically update and refresh but if you are offline they should continue to function transparently to you.

Google developed the open standard in 2015 but it really started becoming popular in 2020.


However, as you might expect there are some additional minor requirements to meet the Google PWA specification and here they are:

  1. must work on all common browsers including Chrome, Edge, Firefox and Safari
  2. must load in less than 10 seconds on old 3G networks
  3. must function properly on different screen sizes/resolutions ranging from normal small cell phones to tablets and even full PC’s
  4. must smoothly allow the user to go backwards and forwards without having the content ‘jump’ around the screen
  5. must use encrypted communication over SSL
  6. must give users an easy method of adding a shortcut to their desktop/home, much like installing an full app


There are many other technical requirements for PWA’s that developers have to pay attention to.  To allow for easy testing and analysis of Progressive Web Apps, Google make a small evaluation tool named Lighthouse available for free.

Lighthouse is used by developers of all sorts of websites but it has particular checks for PWA’s.

If you want more information on PWA’s but don’t want to be overloaded with developer speak, this video will help.



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