Build a scalable web application

How to Build Scalable Web Applications?

Estimated read time: 10 minutes

Interested in building scalable web applications? 

This is a very important question for all application creators. 

Entrepreneurs planning to launch a web app this year must consider scalability. If you are an entrepreneur, and your business strategy envisages significant business growth, you need to know how to build a scalable web application.

Setting the context: Web app vs. website

Before proceeding with the guide on building scalable web applications, I would like to set some expectations. I will talk about how to create a scalable web application, not a website. Many Internet users often use the word ’website‘ for everything on the Internet, however, there‘s a subtle difference.

A website is primarily informational, i.e., users visit it to view content. On the other hand, web apps are interactive platforms where users perform specific tasks.

Read more about their differences in this Quora Q&A thread. Gmail is a web app, however, is a website.

What Does a Scalable Web Application Look Like?

infrastructure of a scalable web appkication

A scalable web app is one that can handle an increased workload. There are various ways in which an increase in workload can come about. For example, the web app may need to deal with a larger amount of data.

The web app might need to handle requests at a higher rate. There can also be a combination of a higher volume of data and a higher transaction throughput requirement. Read more about scalability in this Q&A thread in Stack Overflow.

There are different interpretations of web application scalability. We say a web app has “scaled up” when the higher scalability is a result of strengthening the hardware. On the other hand, “scaling out” denotes adding more hardware.


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There are also other ways to talk about scaling, e.g., “vertical scaling”, and “horizontal scaling”. You add more hardware resources to achieve vertical scaling. On the contrary, you design or architect your application to handle more parallel traffic in case of horizontal scaling.

Benefits of a Scalable Web Application

Entrepreneurs get significant benefits if they build scalable web applications. The benefits are as follows:

  • The system can handle a higher load. This way, you as an entrepreneur can grow your user base. Building a scalable web application with scalability principles keeps your customer acquisition cost within a reasonable limit. You don‘t have to spend a disproportionate amount of money to acquire new customers.
  • When you make a scalable web app, you should be able to add new features seamlessly. Read more about it in this Quora Q&A thread.
  • A scalable system should scale well across different geographic regions.
  • Good scalable web app principles ensure that the maintenance costs grow at a reasonable rate when the system scales in all the above aspects.

Examples of Highly Scalable Web Applications

It‘s a tough world out there! When you launch your web app, you will likely compete with players already commanding significant market shares. A highly scalable web app increases your competitiveness.

Take a renewed look at the popular web apps, and you intuitively understand how their scalability helps them.

There were 1.5 billion Gmail users as of October 2018, as this report states. Trello, the popular project management web app reached a user base of 25 million in September 2017, as this announcement states.

Factors That Influence the Scalability of a Web App

scalable web application projects

Multiple factors affect the scalability of a web app, and there are as follows:

  • A scalable app architecture plays a key part.
  • Frameworks significantly influence the web application scalability, therefore, the right choice of framework is important.
  • The design of the app needs to follow certain best practices for it to remain scalable over the long run.
  • Load testing by the project team assumes importance here. The simulations should be realistic.
  • The choice of hardware platform affects the scalability.
  • The API economy is in full flow, therefore, you will likely consume 3rd party services via APIs, i.e., ’application programming interfaces‘. How these APIs will work has an impact on your web app scalability.

Read more about these factors in “The Basics of Scaling Java EE Applications”.

How To Create a Scalable Web Application?

Let‘s review the steps to build scalable web applications.

Step #1: Manage stakeholder expectations regarding web application scaling

If your web app is already scaling according to your business plan, then it‘s already supporting your business growth requirement. Don‘t try to improve scalability when you don‘t need to. You should do the following:

  • Collect data to verify that your web app is indeed supporting your business strategy in terms of scalability.
  • Explain to your business stakeholders that projects to scale up and scale out can be costly.
  • Clearly communicate to the stakeholders that such projects can add complexities to the system and adding features in the future could become harder.
  • Set your business stakeholder expectations such that you don’t unnecessarily take up such projects just because everyone else is talking about scalable web apps.

Please read more about the importance of this in “Scaling your web app 101: lessons in architecture under load”.

Step #2: Define your web application scalability challenge using metrics

Let‘s go forward, and we will assume that your web app is indeed encountering scalability challenges. You need to define your specific scalability issue, therefore, you need to use the right metrics. At a high level, there are four scalability metrics to analyze, as follows:

  • Memory utilization;
  • CPU usage, where a high usage typically indicates that the app will not perform well;
  • Network I/O;
  • Disk I/O.

Read “8 key application performance metrics & how to measure them” to gain more insights into the relevant metrics.

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Step #3: Use the right tools to monitor the web app’s scalability

Now that you have decided on the metrics to focus on, you need to regularly monitor the performance of your app concerning those metrics. If you are managing your own infrastructure, then you need to invest in a good ’Application Performance Monitoring‘ (APM) solution.

New Relic, AppDynamics, etc. are reputed APM solutions. You can find more examples in “Best APM tools”. If you are using a ’Platform as a Service‘ (PaaS) account, then it‘s easier!

Prominent PaaS providers offer good application monitoring solutions, which makes your work easier. For example:

  • If you are using the Amazon Web Services (AWS) Elastic Beanstalk, it has its‘ own inbuilt monitoring solution.
  • Heroku, another prominent PaaS uses its‘ own New Relic add-on for monitoring.
  • IBM Cloud PaaS provides its‘ monitoring service as part of its catalog of services.
  • Microsoft Azure PaaS also has its‘ monitoring solution.

Monitoring solutions typically provide valuable insights. These should help you in pinpointing your focus areas.

Step #4: Use the right infrastructure options for scalability

I recommend you engage a PaaS provider for your web app since it makes a lot of sense for entrepreneurs. PaaS is a cloud computing model where the managed cloud services provider takes care of many aspects, e.g.:

  • Infrastructure;
  • Networking;
  • Servers;
  • Storage;
  • Middleware;
  • Operating system (OS);
  • Runtime environment;
  • Database;
  • An ability to integrate with 3rd party service providers easily.

You bring only the application code and data. PaaS providers have ’Service Level Agreements’ (SLAs) for availability, reliability, etc., and they offer auto-scaling. Entrepreneurs don’t need to make a large upfront investment in their IT infrastructure, moreover, managing scalability becomes easier.

Adding additional infrastructure resources to scale your web app is typically very easy with PaaS providers. They provide flexible pricing plans, including ’pay as you go‘ options. Following are examples of a few prominent PaaS providers:

  • AWS Elastic Beanstalk;
  • Heroku;
  • Microsoft Azure PaaS;
  • IBM Cloud PaaS.

You can find more examples in “10 top PaaS providers”.

Step #5: Select the right architecture pattern for scalability

A large-scale web application architecture is a key consideration while building a scalable web app. Architecture issues can significantly impact scalability. There are numerous architecture patterns, and I have explained them earlier in “Large Enterprise Java Projects Architecture”.

Two examples will illustrate the importance of the architectural pattern, as follows:

  • Suppose you are building a web app tool that will likely have a heavy user base. The nature of the tool is such that there are repetitive functions that all users will use frequently. In addition, there are other functions that users may not use that frequently. You will do well to bundle the repetitive functions together and offer everything else over it as plugins. In this case, you will benefit from using the microkernel architecture pattern.
  • The other example involves you building a web app with potentially high user volume but with several diverse features. Each feature can work independently. Features have varying demand profiles, i.e., they will have their peaks and troughs at different times. This means you will need to scale them separately. You will also add features in the future, moreover, they will also be independent. This makes the microservices architecture suitable for you. Read more about it in “10 best practices for building a microservice architecture”.

Note: I have earlier recommended using a PaaS provider. This will help you if you select the microservices architecture since PaaS providers make it easier to implement it.

Step #6: Achieve scaling with the right database

For scaling, the database is an obvious focus area after you have addressed the infrastructure and architecture aspects. Note that there are no ’one-size-fits-all‘ recommendations when it comes to databases. You need to do the following:

  • Analyze your web app requirements minutely. Consider what kinds of data you will store. Will it be relational data only? Do you also need to store ’disconnected‘ data, i.e., data that has no transactional relations? Are you storing both kinds of data?
  • You will need a relational database management system (RDBMS) for your relational data. MySQL and PostgreSQL are good RDBMS options with high scalability.
  • You will need NoSQL databases for your ’disconnected‘ data. MongoDB is a highly scalable NoSQL database. You can find more examples in “The best NoSQL database options for your business requirements”.
  • Finally, whichever database you choose, you will need to integrate it into your app. If you use a reputed PaaS provider as I recommended, you will find it easy to do so since most PaaS providers have excellent documentation to guide you.

Step #7: Select a framework that aids scalability

It‘s time we focus on the development framework since it has a noticeable impact on scalability. Depending on your choice of the development language, you have quite a few options, as follows:

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  • If you prefer Java, then you can consider the tried-and-tested “Spring” framework. There is excellent documentation, moreover, your development team might already know this. You can check out other options in “The 10 best Java web frameworks”.
  • Ruby on Rails is an excellent option. Note that Heroku, one of the PaaS options I have mentioned has a high degree of capability with it.
  • If you like Node.js, then js is a great option.
  • You can find other framework options in “Top 10 backend web development frameworks”.

Have a More Complex Web Application Scalability Requirement?

Do you have a more specific and complex web application scalability project at hand? This could be due to many reasons, e.g., you might need to meet specific data privacy-related regulatory requirements. In such cases, you may not be able to use a public cloud infrastructure that all PaaS providers commonly offer.

You might need to use a private cloud, or the requirements might prompt you to use a hybrid cloud. There are reputed cloud solution providers that can help you with it, e.g., “AWS Cloud Computing Services”, “Google Cloud Platform”, and “Microsoft Azure Cloud Computing Platform and Services”. However, you encounter more complexity.

You need a team with appropriate skills, meaning that you have to hire web developers, business analysts, IT architects, designers, testers, and project managers, you might need cloud platform architects in this case.

Moreover, projects like this can benefit from Agile methodology, therefore, check out our guide “How to build a Scrum development team?” before you onboard a team.

Assembling such a development team with niche skills can be hard depending on your geography, moreover, you need to manage the project end-to-end. Consider engaging a development partner.

Our guide “How to find the best software development company?” can help you with the due diligence.

If you are still looking for an experienced web application development partner, DevTeam.Space can help you via its field-expert software developers community.

You can easily partner with these vetted and managed software developers by writing us your initial project requirements via this form. One of our account managers will contact you to discuss in detail how we can help with the software development and management process.

Frequently Asked Questions on Scalable Web Applications

What are scalable web applications?

Technically, all apps are scalable applications. The term refers to making changes to an application’s infrastructure so that it can handle an increasing number of users.

How do you scale a web application?

It is likely that you will need to examine new infrastructure possibilities. While you might need to make software updates, this is not always a necessity. You will need to focus on your framework and other performance-related elements of your web application’s infrastructure. For more information, read this article.

Where to find developers to scale an app?

DevTeam.Space is a community of field expert software developers. The platform has built and scaled numerous applications so has all the expertise that you require.


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