Programming Languages Used by Popular Websites: What SMEs Should Know

When a business owner asks, “What programming language should my website be built in?”, the answer is rarely straightforward. But looking at how the world’s largest websites are built offers a useful frame of reference, not because your business needs to replicate Facebook’s infrastructure, but because the patterns behind those choices reveal principles that apply at any scale.

This guide covers the languages powering the most visited websites on the internet, what drives those choices, and what the patterns mean if you are making technology decisions for your own business.

What Languages Power the World’s Biggest Websites?

The table below covers the primary languages used by major global platforms. Most large-scale websites use multiple languages across different parts of their stack; the entries below reflect the dominant choices in each case.

The immediate observation is that JavaScript appears in every row. That is not a coincidence.

JavaScript: The Universal Front-End Language

JavaScript runs in the browser. That single fact explains its ubiquity: any website that wants to respond to user actions without reloading the page uses JavaScript. Clicking a button, submitting a form, playing a video, updating a feed in real time, all of this is JavaScript at work.

According to W3Techs, JavaScript is used as a client-side language by approximately 98% of all websites. [Editor: verify current figure at w3techs.com before publishing.] The figure has remained consistently high for over a decade because there is no viable alternative for in-browser scripting at scale.

For businesses commissioning a website, JavaScript’s presence is essentially guaranteed. The more relevant question is which JavaScript framework your developer is using, React, Vue, Angular, or plain JavaScript, and whether that choice suits your project’s size and long-term maintenance needs.

Java: The Backbone of Large-Scale Backend Systems

Java’s presence at Google, Amazon, Netflix, and Tencent is a function of one characteristic: it handles scale reliably. Java is strongly typed, platform-independent, and has a mature development community of libraries and tools built up over three decades.

At Amazon, Java has been a core language for backend web application development since the company’s early years. At Netflix, it powers the backend systems that manage content delivery, account management, and recommendation logic behind the scenes. The front-end experience you see is largely JavaScript; the infrastructure that makes it work is substantially Java.

For SMEs, Java is not typically the starting point for a website build; it requires significant development resources and is better suited to complex applications than standard business websites. Its relevance is as a signal: when you see Java in a stack, you are looking at a serious investment in engineering capacity.

Python: The Versatile Choice for Data and AI

Python’s rise across major platforms reflects two things: its readability makes it faster to develop with, and its development community for data science and machine learning is unmatched.

Amazon and Pinterest both use Python extensively for data processing and recommendation systems. Google uses Python across research and tooling. Its straightforward syntax has made it one of the most widely taught languages, which in turn means the developer community is large and the pool of available talent is deep.

For businesses with ambitions in AI, data analysis, or automation, Python is the language most likely to sit at the centre of that work. ProfileTree’s digital strategy team regularly encounters SMEs that have started collecting data without a clear plan for using it; Python is frequently the practical answer for turning that data into something actionable.

PHP: More Prevalent Than Many Developers Admit

PHP has a reputation in developer circles that does not reflect its actual market share. It powers a substantial portion of the world’s websites, including WordPress, which runs approximately 43% of all websites globally (W3Techs, 2025). [Editor: verify current figure before publishing.] Facebook’s original architecture was built in PHP, and the language remains in their stack in a modified form called Hack.

The reason PHP persists is straightforward: it is easy to deploy, well-documented, and has a massive community. For businesses running a WordPress site, PHP is the language underneath everything, even if neither the business owner nor their developer thinks of it in those terms.

“Most of our SME clients don’t need to know what language their website is built in,” says Ciaran Connolly, founder of ProfileTree, a Belfast-based web design and digital marketing agency. “What they need to know is whether the platform is well-supported, whether their developer can maintain it, and whether it will grow with the business. For the majority of clients, WordPress, built on PHP, answers all three.”

TypeScript: JavaScript With More Structure

TypeScript is a superset of JavaScript that adds static typing, which means developers declare what type of data a variable will hold, rather than letting the language figure it out at runtime. This catches a significant class of bugs before code ever runs.

Microsoft developed TypeScript and uses it extensively across its own platforms. It has been adopted by large engineering teams building complex front-end applications precisely because it makes codebases easier to maintain at scale. YouTube reportedly uses TypeScript across a substantial portion of its front-end codebase.

For SMEs, the practical implication is: if you are building a complex web application rather than a standard business website, TypeScript is a signal of engineering rigour in your development team.

Emerging Languages Worth Knowing

Three languages are worth noting for businesses planning technology investments over the next three to five years.

Go (Golang) was developed by Google and is built for performance and concurrency, handling many tasks simultaneously without degrading speed. It is increasingly common in backend infrastructure and API development, and its adoption across cloud-native applications is growing steadily.

Kotlin has become the preferred language for Android app development, used by the majority of professional Android developers according to JetBrains’ annual developer survey. [Editor: verify current percentage.] If native Android development is part of your plans, Kotlin is the current standard.

Rust is optimised for systems programming where performance and memory safety are both critical. It is being adopted by projects ranging from web browsers to operating system components. For most SMEs, Rust is not a direct consideration, but as it becomes more common in infrastructure tooling, its presence in a developer’s skill set is a credibility signal.

What This Means for Your Business Website

The languages used by Facebook and Netflix are not the languages your business website needs. The relevant takeaway from studying enterprise stacks is understanding the principles behind the choices, stability, community support, scalability, and developer availability.

For most SMEs commissioning a website, the practical framework is simpler:

WordPress, built on PHP, covers the vast majority of business website needs. It is well-supported, widely understood, and has a development community deep enough that you will never struggle to find qualified help.

If your project requires a custom web application (a booking system, a client portal, a data-driven tool), then the language choice becomes more significant. JavaScript (often with a React or Vue framework), Python for any data or AI component, and a clearly documented API architecture are the foundations of a sensible modern web application build.

If you are evaluating a web development partner, asking about their stack is a legitimate due diligence step. A well-run agency will explain their choices in terms of your project requirements, not its own preferences. ProfileTree’s web development team works primarily in WordPress for business websites and selects additional tools based on what each project actually requires. You can find more details on our approach to website development for SMEs on our services pages.

For a practical guide to checking what language any website is currently built in, see our separate article on [how to identify the programming language of a website], a useful tool when you are researching competitors or evaluating platforms.

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