Web Application
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A How-to Guide on Building Scalable Website Application

By Unni MohanDec. 20, 2022, 3 p.m. Application development company
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A complete guide on how to build a website application that can easily scale & grow with your business. Learn how to set up, design & deploy an app that can handle growth

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Building Scalable Websites – A How-to Guide

Any web app should be developed with the ability to scale easily, whatever the sector for which you are building the app. It is a good idea to expect an influx of users at different times and build the system so that it can handle the traffic. 

Website scalability must be factored in even before the development stage is started.

In this post, we list the dos and don’ts of building scalable web applications and the factors that have to be kept in mind to create scalable web applications that can process large amounts of data without downtime.

What are Scalable Web Applications?

Scalable web apps can cope with a suddenly increased number of users that simultaneously interact with the application. A scalable web application would perform in the same manner with one or a thousand users at a time. 

Consequently, a scalable web application performs equally well with either one or a thousand users and stands ups and downs of the traffic.

Principles of a scalable web application

Scalability of a Web App – Influencing Factors

A clean code design and the app architecture are what plays an important role in building scalable web applications. Choosing a good framework based on your requirements decides the performance of the application.

Perform load tests to locate weak spots in your app and once you overcome them, a smooth performance can be expected.

Choosing the appropriate hardware is yet another important factor. 

Select high-quality third-party services for fewer operational failures. 

What are the Different Types of Scalability?

Cloud computing refers to horizontal, vertical and diagonal scalabilities. Horizontal scaling refers to adding more machines to the server whereas vertical scaling refers to adding more computing power to the machine. Diagonal scaling refers to a combination of the two.

Read our blog “A How-to Guide on Building Scalable Website Application”.

This concerns the web design process and TCO which include the cost of development, operation, and maintenance. Striving to use working parts instead of building new systems from scratch may help to save on expenditures. This helps to balance the application development costs to a large extent. 

Other factors to control expenditure would be to build open-source software using common web design technologies. This can open you up to a large community and you can get in touch with experts to help you contend with challenges in the future and become a part of your team. 

Scalability of Maintenance

Use platforms and tools that facilitate tracking the application regularly, schedule and apply updates when required, and ensure continued app efficiency. These will ensure regular maintenance and management of the server and the application software.

Design Principles of Scalability

1:  Choose Horizontal Scaling Over Vertical Scaling 

Sometimes, the system is limited to scale horizontally. However, this extends databases in the same direction. Also, it is easier to just       add one more server than upgrade the existing one. This way it is cheaper. 

2:  Remove Work From the Core

It is better to have many services doing small jobs and distributed systems will clear up many scaling-up bottlenecks. The number of clients will always exceed the number of services that you have. 

3:  API First

It is good to have a web application that functions like an API. Clients using any app today first connect to the API. The API does not distinguish one client from another and just keeps serving them.

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4:  Cache Everything

Cache stores data that can be retrieved faster as answers to queries in the future. Caches, therefore, significantly improve the scalability and performance of web applications.

5:  Maintenance and Process Automation Design

Regularly monitoring the system with appropriate software updates and maintenance of the app will ensure smooth performance. 

6:  Choose Asynchronism

Implementing an asynchronous method between the client and server in the web application plays a significant role in communication. When the users submit a request, we can keep them informed about a successful deal and provide updates while the query is still being processed.

7:  Statelessness in your App

Statelessness is very relevant for distributed architecture systems supporting horizontal scalability. When the components remain stateless, it is easy to redistribute them in case of a breakdown and they can be scaled quickly to adapt to load changes.

Scalability vs. Fault Tolerance

It is a common thought that adding a second server may help to avoid a system breakdown. Scalability can also be brought into effect by dividing the database into two and putting them on two separate servers. 

Read our blog : Top 5 Factors contributing to the Success of a Web Application

In such a case, if one part crashes, the whole system will fail and, therefore, is not recommended. It is a good idea to implement the following:

  • Prevent single point of failure
  • Do not rule out failure. Ensure that users do not even realize there is one.

Importance of Establishing Scalable Web Applications

Scalability is an important component of any web project — whether for a start-up or an existing web app. Scalable websites can handle heavy workloads better, strive to keep response time constant, help to simplify server maintenance, and also help to decrease operational costs. Overall, there are many advantages that a scalable application brings along.

The Standard Architecture of a Web Application

Using standard architecture brings about many advantages for web app development. It ensures simple navigation between the files and brings about better flexibility of the system for future scaling.

The Fundamental Components of a Standard Web Application are as Follows:

The front-end part of the application directly interacts with the user. If users perform too many actions simultaneously, the front end may lag. In such a case, you may have to split up the app into pages while using a virtual scroll. However, most issues that users encounter on the front are caused by the backend.

The back end is not accessible to the users but reflects in every step that the user makes on the front end of the application. The backend significantly influences the performance of any application.

Read our blog : Progressive Web Apps: Why Your Business Needs It?

The database is used for data collection and storage. It is designed to be easily accessed, managed, and updated by the computer system.

If you build a project with scalable web application architecture, correct scaling of all the available components should be ensured. It is also critical to use the right technology stack that will work to enhance the web app performance.

Database Scaling

It is possible that the database server would have an enormous amount of data volume and may require separate servers. Scaling this can be supported by distributing the computing processes and indexes. 

Computing Processes Distribution

By adopting this, you can decrease server load by splitting the complex calculation processes in the database. Here, each server receives a full copy of the database to handle specific work portions. Though difficult, this can be done in a few ways. 

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Database sharding involves splitting the datasets into logical partitions and adding them to each server. Each server stores the data of only some users, and, therefore, all requests from one user go only to one server. When the number of users increases, you can add more servers. Data can be also distributed between servers by date.

Replication allows a full database copy on each of the servers, and each client can read from any server. This betters the performance but works only if the data fits on a single server. In case of lots of data and a heavy load, a combination of these methods can be used.


Database performance is optimized by minimizing the number of disk accesses when processing a user request. Adding indexes to your website architecture will help in enabling faster reads as the data and servers increase.

Scaling the Backend

Even with a solid and reliable back-end, it doesn’t mean the traffic will never change. If there is continuous load growth causing unstable operation, it is time to take care of the backend scaling of your application. Here, the principle of dividing user queries between servers has to be considered.

Read our blog: How Microservices will help you develop a better web application

When applying this to web applications, you have to allocate queries equally between the computers. This will help to remove the load from the main hardware and redirect it to another server.

Balancing Node

This technique makes use of distributing devices in order to make the application scalable and thus protect backend overloading. If the number of queries keeps on increasing, the balancers will then allocate connections to nodes. With the addition of more nodes, the service performs better. 

Client-Side Balancing

When there is server-side balancing, There should be client-side balancing as well. Here, the load balancers disappear and clients will get an opportunity to select the server they want to connect with. This can improve latency and scalability, but with additional complexity.

Cost of Building Scalable Web Applications

Cost control for building scalable web applications depends on many factors. The size of the company, however, directly affects the choice of cost strategy.


For start-up companies, it is better to use cloud services and a pay-as-you-go option than buy and maintain their hardware equipment. They will also need to hire and train a team of administrators.

Big Businesses

Large businesses have to maintain critical infrastructure and maintain full control over data within the organization. Therefore, it is profitable (costs and security) for big businesses to maintain their servers.

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It is vital in both cases to have tools for cost analytics and the presence of a team of specialists to supervise the use of resources and also make recommendations for optimizing costs.

Examples of Scalable Web Services

Slack is a standard communication tool in the IT industry. It uses microservices that help to provide real-time communications, screen sharing, and video calls to millions of daily active users.

Bitly is built using microservices architecture to provide link optimization services. It creates decentralized structures and isolates component failures to support clicks to the tune of 20 billion per month.

Dropbox is one of the most popular file-sharing services that use an orchestration tool. It manages distributed database services across stand-alone clusters. It can store more than one million files per 15 minutes.

Final Note

Whatever the project you want to build, whether a small website or a complex app, scalability is a factor to be considered. The number of visitors to your website application will gradually increase in proportion as your project grows in size. Scalable web applications would be able to handle the increased workloads and provide stable performance to the users. 

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A scalable app can handle a sudden increase in the number of users and heavy loads without compromising performance or disrupting the user experience. That is, the software package can expand or shrink according to the number of users and data load.

Some of the factors that affect scalability are web architecture, selection of a suitable framework, choice of hardware and third-party services, etc.

Choose horizontal scaling Remove work from the core API first Cache everything Maintenance and process automation design Choose asynchronism Statelessness in your app

The two basic types of scalability that you encounter in cloud computing are vertical and horizontal scaling.

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