Web applications today have to be intuitive, engaging, and functional to interest its demanding audience. People are actually fed up with the plain non-responsive informational websites and demand more interaction and engagement from the products they are using. More and more services and businesses shift towards web apps to get closer to their customers. The trend is obvious since the number of app downloads increased by a third from 2016 to 2018 (Statista).

So no wonder that web developers get involved in app development processes more and more. In this article, you will learn the basics of web application architecture and the main elements that constitute an effective web app.

Web application architecture in a nutshell

Web application architecture defines the way of how components in a web app interact with each other. This concept can be applied to the components or features of UX/UI constituents, such as statistics, notifications, settings, etc. However, this is not the focus of this article. These are structural components that interest a web developer: client and server.

The client in this context means some feasible representation of a web app that faces the app’s users. So basically, this is the layer of a web application with which users can interact directly. This layer is called front-end development with three basic languages: HTML, CSS, and JavaScript. It already exists inside of a browser, so users don’t need to address any third-party adjustments to access it.

The server’s side is the back end of a web app. It is developed with the back-end languages, such as PHP (slowly but steadily sinking into the oblivion), Python or Java (as two most progressive ones for today), .NET, Ruby on Rails, and many others. The back end needs to consist of at least two main elements: logic (control center) and database. Logic will control all the operations and the database will store all the data.

3 typical operating models for a web app

Operational models for web applications must be selected based on the requirements your business or customer has.

1 server that fits it all

Such web apps have only one server that executes two functions: operational and database. This means that whenever a user is doing something on their level, you have only one server to process and store all the data. As you probably see, this is a pretty risky undertaking since if your server goes down, your app goes down, and you lose it all at once.

Application: test project or some internal business operations that do not include external customers.

2+ servers & 1 database

Such stateless architecture means the database and servers are separated. It allows your web app to scale web servers horizontally. This means that you will have to physically separate operational servers from your database and run them on different machines. In this way, servers would process all client-sent information and then store the results of such inquiries in a database without making any notes about such operations. In this way, you can easily increase the productivity of servers and your web app. Furthermore, such web apps are more reliable: if one server goes down, another one picks up its load and the app continues to work for the users. Of course, a crash of a single database will stop your web app from running, so this model is still not perfect for the contemporary market.

Application: primitive apps not directed towards large markets.

2+ servers & 2+ databases

As expected, this is the most secure and agile architectural model for a web app. It also has two types:

  • 2+ databases store identical data hence duplicating one another. Most often, in this case, two databases would do the trick. You don’t need to triple all the information since it is an extremely rare case that both databases would go down simultaneously.
  • Each database stores its own piece of data. In this case, should one of the databases crash, the app might lose some information temporarily (some users will not be able to log in, for instance), yet will continue to run.

Model #3 is the most failure-proof one. Should any element fail, the rest of the system will take over its functions and continue to run. Keep in mind that if you are planning to use five and more servers or databases,  you need to install load balancers to control the information flow.

Application: any modern software that interacts with customers and is expected to experience major data flows.

Types of web application architecture

Regardless of the model, all web application components always work simultaneously and create an integrated system. Depending on how the app logic is distributed among the client and server sides, there can be various types of web application architecture.


This system has been out there for ages: here, the app’s server sends to the end-user a complete HTML page. Whenever the end-user wants to get an update, they send the request to the server, which then sends the entire HTML page back. In this type of web application architecture, both client and server operate with a complete set of data which, if changed, needs to be updated in total. This means that all the data is stored on the server, and customers cannot access or influence it. Whilst this is a secure type of architecture, be ready that it requires quite a powerful system to reload the page many times, especially with large amounts of data. Most often, the good-old HTML architecture is used for ordinary websites rather than web applications.


Whenever you develop a widget web app, you have app’s page logic that is constituted with web services. As a result, every page an app’s user sees has widgets (separate entities). In such an architecture, widgets send AJAX queries to the services and then receive only pieces of information in JSON or HTML format. As a result, instead of reloading the whole page in the app, the system only updates those widgets making the system more agile and friendly for mobile devices. Be ready, however, that widget development requires much more time and knowledge, especially considering that widgets with app logic are exposed on the users’ side; hence the app’s security might become a concern here.

Single-page architecture

Web app architecture of this type is the newest and accepted among developers around the world. In this scheme, a user downloads one page only once. On top of this single page, there is a “coating” of JavaScript that communicates with the server and instantly demonstrates all the changes that the user requested to be made. As a result, users do not reload the page (as in the first type), but only reload the top coating of a page. Since users generally make very small changes to the pages, such web application architecture is believed to be most dynamic, light, responsive, and user-friendly.

To sum up

Web application architecture may consist of different components and run on different types of logic. The selection of the most suitable option for your company heavily depends on the scope of expected traffic to the app as well as the content that will be displayed. First, go through your goals before getting down to developing your new web app.