10 January 2023

How to Scale Web Application: The Best Techniques


If you have built a web application, you surely want it to become a commercial success for your company. Any successful owner of such a product will tell you, though, that having a large number of users flock to your app has its challenges.  

One of them is managing the potential of your application to cope with an increasing number of users interacting with it at the same time. Scaling a web application is no easy feat, but it is certainly possible - this blog post will tell you a bit more about it. 

What is app scaling? 

When an increased number of users want to interact with your app simultaneously, connecting to one server, there is a high chance that your app's performance will drop significantly or the server will run out of memory and stop responding. In such cases, the app needs scaling. 

App scaling is the process of increasing (or decreasing) the resources allocated to the app based on demand. It is done to ensure that the application is working and responsive. It can be done in various ways, such as by changing the number of servers connected to the application or adding more memory or processing power to a single server. App scaling is essential to running a successful application since it guarantees that it can manage peak usage periods and has the resources to respond to customer demand. 

Why is scalability important? Does your web app need it? 

You don't want your app to stop working correctly suddenly. If it stops responding or becomes unavailable all of a sudden, it will likely lose users, and in most cases, that means loss of profit. The application has to grow along with the number of users, as it needs to be able to handle more and more requests per minute (RPMs). 

There is no point in creating web applications with no potential for future growth. The market proves such ideas do not meet the expectations and needs of app users and, therefore, usually do not succeed on the market. That is why it is critical to plan for your app's future growth and design it in such a way that its capabilities can be easily extended and improved. 

If the app does not provide a high-speed service and efficient operation, people will not be too interested in using it. You can add new CPUs or increase the memory limits, but it won't change the application's overall performance. 

This is a scenario that everyone wants to avoid, but how do you do that? What methods can you use to effectively scale your app to prevent this from happening? 

The truth is that if your web app can not support a higher server load, it is too late to do anything about it, and that is why you need to think about scaling web applications during software development. 

Also read: The Best App Development Guide to Building Your First Mobile App

Types of scalability tactics 

If you have googled the term already, you have likely noticed that there are different web application scalability types - the main two being horizontal scaling and vertical scaling. The third one is diagonal scaling, which combines the former two. 

Knowing what kind of scalability you need for your web applications is crucial since it's critical to your success. It also helps to understand how each kind operates and which is ideal for your company. If you want to create a scalable app, you need to know the basics. 

Horizontal scaling 

Horizontal scaling, also known as scaling out, refers to adding multiple servers or nodes to your system, increasing the overall capacity of your web applications. This minimises the server's load by dividing the task among the additional nodes.

Theoretically, adding more machines to an existing pool means you are no longer limited to the capacity of a single unit, allowing you to scale with minimal downtime. Horizontal scaling is a distributed architecture pattern where you add more servers to serve the same purpose to lower the risk of performance issues. In this method, just one load balancer can help tremendously by sharing the load among multiple servers. 

Advantages of horizontal scaling: 

  • Low downtime 
  • Limitless scaling possibilities 
  • Better fault tolerance
  • Easy to upgrade and simple to implement
  • Increased performance as the load is delegated among multiple machines 

Disadvantages of horizontal scaling: 

  • Less consistency (joins require cross-server communication) 
  • More coding may be required
  • Any bugs in code will be more complex to debug
  • The cost of the data center can increase, as more space and power is needed
  • Initial costs are higher, as adding new servers is more expensive than upgrading old ones  

Vertical scaling 

Vertical scaling entails adding extra computational power (like CPU or RAM) to your current nodes. The data is stored on a single node, and scaling is done by using multi-core, such as by dispersing the load across the machine's CPU and RAM resources.

Vertical scaling is most commonly used for applications by small and medium-sized companies since it allows them to scale faster than horizontal scaling. Vertical scaling is an attractive option because it is relatively easy and cost-effective compared to horizontal scaling. The term vertical scaling is used because it refers to increasing the capacity and performance of an individual server by adding more memory, CPUs, or other resources. 

Advantages of vertical scaling: 

  • The cost of the data centre is smaller 
  • It is simple since everything runs on one machine 
  • The server costs are lower
  • Little code change needed to scale
  • Less complex process communication with a single node 

Disadvantages of vertical scaling: 

  • There is a limit to the amount you can upgrade 
  • You are restricted to one vendor
  • Higher downtime possibility, unless you have a backup server
  • Having all your operations on one server increases the risk of losing all data in case of a failure 

What to consider when developing a scalable web application 

There are several important things you have to keep in mind when developing a scalable web app: 

  • The need for scaling - first, you need to assess what could be the customer demand your app will be dealing with. This will help you determine if vertical scaling is the most suitable option for your application or if horizontal scaling may be more cost-effective in the long run. 
  • Scaling metrics - using data and metrics relevant to your system is crucial. This can help you build a comprehensive system performance profile and pinpoint areas where optimizations could be made. 
  • The tools - what will you use to measure the performance of your web app? There are many tools to choose from, so pick the one that fits your project the best. 
  • Suitable infrastructure - will your infrastructure be able to deal with the heightened demand? Remember that a fault-tolerant infrastructure can change a lot. 
  • The right software architecture pattern - choose the one that will allow you to achieve high stability. The right software architecture pattern is critical to the scalability process.
  • Correct database - database management is crucial in effective scaling, so you need to choose a proper database engine.
  • Proper framework - If the application is built using old frameworks, its potential will be limited. Therefore, choosing the right ones is essential to ensure high stability and scalability.
  • Reliable deployment - what would be the best approach to your app deployment strategy to ensure the best performance and speed? Deployment strategies can be crucial for scalability, so it is important to consider various approaches and architectures, such as microservices and containerization.
  • Security - ensure security while developing a scalable web application. Keep an eye out for vulnerabilities and flaws. Utilizing cloud-based services and a DevOps workflow when scaling your web app are great options to enhance security while scaling up. 

Useful tips for application scalability 

Many considerations must be made to successfully scale your web application. Here are some suggestions to make things easier for your company: 

  1. Set realistic goals: the IT team has to be able to handle the workload, and there is no point in setting up for a demanding way bigger than expected. 
  1. Consider open source solutions: For cost-effective and quickly scalable infrastructure, you can use an open source one, like Kubernetes, when building your web application. 
  1. Optimize SQL queries: Scale the databases to serve heavy workloads. When a user logs in, a database query is executed to get the user at each request - with thousands of users this might easily slow down the web app. 
  1. Test performance during the product development phase: Testing your web app's behaviour in various situations can help to determine whether it is scalable or not. 
  1. Do not overengineer: There is no point in building software meant for tens of millions if your target is just several thousand users. You need to know what your projected user base is realistically. 

Scale your web application for better performance 

While the vertical vs horizontal scaling debate has been going on for years, there is no definite answer to which option is the best for scalable applications. 

What is evident is that scalable web programmes are far easier to manage than non-scalable ones, though. Whether you use cloud services or your own storage solution, an app that can properly handle the database queries and the activity of all its users is more likely to succeed on the market than the opposite. The proper scalable web app architecture means smoother performance and fewer issues with incoming clients. 

Remember that you need to think about your app's scalability from the very beginning. You may only have a few users at the start, but if you expect a large number of clients simultaneously connecting in the future, you have to keep that in mind way before deployment. 


Karol Rogowski
Head Of Engineering

Working in IT since 2009. Currently working as Head of Engineering at SoftwareHut and as an academic teacher at Białystok Technical University. Co-founder of meet.js Białystok. Book and articles author. Father, husband, huge H.P. Lovecraft fan and terrible poker player.