Tool vs Library vs Framework Key Differences Explained Simply

When opening the package.json of a web project, we often see a bunch of names: React, Vite, ESLint, React Router, and Next.js. They are all installed as packages, used for web development, and some even work together in the same project. So why is React called a Library, Vite called a Build Tool, and Next.js called a Framework? Or is a Framework actually just a Library with more features?

The answer is that they are not categorized by size or the number of features. The difference lies in which part of the project each technology is responsible for, and how much it dictates how we write or structure our app. React identifies itself as a Library for building user interfaces, while Next.js identifies as a React Framework for building full-stack web applications. Meanwhile, Vite is clearly a Build Tool that helps manage running the project during development and building it for production. But before we look at how each type differs, there is another concept we need to separate first.

Being installed via npm does not mean they are the same type of thing

Many people start getting confused here, because whether it's React, Next.js, Vite, or ESLint, we find their names on npm. However, npm is simply a channel for publishing, discovering, installing, and managing packages; it does not determine whether that package must be a Library, a Tool, or a Framework. npm itself consists of 3 main components: the Website, the Command Line Interface (CLI), and the Registry that stores the packages along with their respective data. Simply put, being on npm only tells us that we can bring that package into our project, but it doesn't tell us what role it plays. It's like buying a screwdriver, house paint, and a furniture set from the same store. All items come from the same store, but that doesn't mean they serve the same function.

What is a Tool?

The word Tool is quite broad in the development industry. We often use it to refer to software that helps with specific tasks in a workflow without dictating the entire architecture of the app. The easiest example to visualize is Vite, which is a Build Tool that has a Development Server for running the project locally and a Build command for generating files ready for production deployment. In a React project created with Vite, we might use a command like this:

Bash

npm run dev

Vite will help spin up a Development Server so we can edit code and see the results conveniently. When we want to deploy, we use the command:

Bash

npm run build

After that, Vite will generate a Production Build according to the project's configuration. But Vite does not dictate what pages the website must have, how the Business Logic should be organized, or what Component the /about route must render. These matters are still things that we, or another Framework, must handle. Another example is ESLint, which is a Linter used to detect and report patterns in the code based on defined rules. It helps the team control the quality and formatting of the code so that it aligns in the same direction.

Therefore, there are many types of Tools that Devs use, such as:

• Build Tool

• Linter

• Formatter

• Testing Tool

• Package Manager

• Debugging Tool

Each tool assists with a different task, and a single project usually uses multiple tools together anyway.

Then, what is a Library?

A Library is a set of capabilities that we choose to call from our code. We are the ones who decide which API, Function, or Component to pick, where to use it, and when. React is the most direct example, because its official website calls React a library for building user interfaces on the web and native platforms. It lets us build UIs from smaller pieces called Components and assemble them into pages and apps. Let's look at a simple Component:

JavaScript

import { useState } from "react";

export default function Counter() {
  const [count, setCount] = useState(0);

  return (
    <button onClick={() => setCount(count + 1)}>
      Count: {count}
    </button>
  );
}

In this example, we are the ones calling useState from React, and we are the ones who determine:

• What the initial state is.

• When to increment the value based on which event.

• How the data will be displayed.

• Which page this Component will be used on.

React helps manage Components, State, and UI rendering, but it does not define the entire system of the app for us. The official React documentation explicitly states that React is a library that does not prescribe how to handle routing and data fetching for the whole app. Therefore, if we start a project with React and Vite, we might have to choose other things to add ourselves, such as:

• Which Router to use.

• How to manage forms.

• What to use for data loading and caching.

• How to structure the folders.

• Whether to do Server-side Rendering or not.

• Where to handle Authentication.

The advantage is that we have a lot of freedom to choose. However, the trade-off is that the team has to be the one to make decisions and maintain the integration of each part themselves.

What more does a Framework do?

A Framework doesn't just provide Functions or Components for us to call; it also provides the structure, rules, and a certain working flow. When using a Framework, we don't get to choose everything as freely as when starting with just a Library. Instead, we have to write code that fits the conventions set by the Framework. Next.js is a clear example. Its official documentation states that Next.js is a React Framework for building full-stack web applications. We use React Components to build the UI, and then use Next.js's capabilities for the rest. Furthermore, Next.js automatically configures some lower-level tools like the Bundler and Compiler for us. The simplest example is the routing system.

Suppose we want to create an /about page using the Next.js App Router. We can structure our files like this:

Plaintext

app/
├── page.tsx
└── about/
    └── page.tsx

Then, write the Component in app/about/page.tsx:

JavaScript

export default function AboutPage() {
  return (
    <main>
      <h1>About Us</h1>
    </main>
  );
}

Next.js uses folders to define URL segments and uses a special file like page.tsx to create the UI for that route. Therefore, app/about/page.tsx becomes the /about page according to the Framework's conventions. We didn't write a Router and explicitly say that /about must connect to AboutPage; we simply placed the file in the correct location, and Next.js handles the routing flow for us. This is the difference that starts to become clear between a Library and a Framework.

The real difference is: Who controls the Flow of the project?

There is an explanation that Devs often use to separate these two terms:

When using a Library, our code calls the Library. But when using a Framework, we place our code in the spots designated by the Framework, and then the Framework calls our code.

This explanation paints a very good picture, even if it's not an absolute rule that can categorize every single technology. When using React, we are the ones calling the Hooks or Components we want. But when using Next.js, we create files like page.tsx, layout.tsx, or other special files according to its conventions, and Next.js will take those codes and use them in its routing and rendering processes.

A Framework therefore often makes certain decisions for us, such as:

• Where certain types of files should be placed.

• How routes are generated.

• How pages and layouts connect to each other.

• Which parts of the code run on the Server or the Client.

• How the build process is configured.

• What types of rendering the system supports.

The advantage is that the team doesn't have to design and stitch together all the foundational systems from scratch. The trade-off is that we must learn the conventions and limitations of that Framework, and we must agree to work within the flow it provides.

Let's try building the same page with React Router and Next.js

To see the difference more clearly, let's return to the /about page again. If we use a Declarative React Router, we can declare routes via code something like this:

JavaScript

import {
  BrowserRouter,
  Routes,
  Route,
} from "react-router";

import Home from "./pages/Home";
import About from "./pages/About";

export default function App() {
  return (
    <BrowserRouter>
      <Routes>
        <Route path="/" element={<Home />} />
        <Route path="/about" element={<About />} />
      </Routes>
    </BrowserRouter>
  );
}

In this code, we explicitly write the relationship between the URL and the Component.

• / uses the Home Component.

• /about uses the About Component.

But in the Next.js App Router, we use the file structure to define routes instead.

Plaintext

app/
├── page.tsx
└── about/
    └── page.tsx

The results seen by the user might be similar, but what differs is how the project describes the routing. The declarative React Router lets us define routing via an API, while Next.js has us follow the Framework's file-system conventions. This doesn't mean one is always better than the other. A project that needs to control the route configuration itself might prefer the first method, while a team that wants a clear, shared structure might find working with file-system routing more convenient.

So is React Router a Library or a Framework?

If this were an article from a few years ago, we might see React Router referred to as a Routing Library. However, its current status holds more nuances. React Router identifies itself as a "Multi-strategy Router for React" and has 3 main usage modes: Declarative, Data, and Framework.

1. Declarative Mode

Suitable for basic routing, such as matching URLs to Components, navigating between pages, and checking which link is currently active.

2. Data Mode

Adds capabilities for Data Loading, Actions, Pending States, and APIs like loader, action, and useFetcher.

3. Framework Mode

Adds Framework-level capabilities such as Route Modules, Type Safety, Code Splitting, as well as rendering strategies like SPA, SSR, and Static Rendering. The capabilities of each mode increase sequentially, but what we have to trade is the level of control over certain parts of the architecture. The React Router documentation explicitly states that we should choose a mode based on the level of control we want to maintain ourselves, or how much we want React Router to handle for us. Therefore, saying "React Router is a Tool and Next.js is a Framework" without context doesn't quite align with its current status anymore. A more accurate answer is that React Router can be used anywhere from a simple router level all the way up to a full-fledged Framework, depending on the mode we choose.

Can Tools, Libraries, and Frameworks be used together?

Yes, and it is very common. A single Next.js project might contain:

A Framework does not replace a Library, and a Library does not mean we won't need to use Tools. Each operates at a different level and is responsible for a different part of the job. Therefore, instead of asking "Should I choose a Tool or a Framework?", a better question is:

"Which parts of this project should the Framework handle, and which parts does the team want to choose or control themselves?"

When should we assemble a React App ourselves?

We can build a React App without using a full-stack framework by starting with a Build Tool like Vite, Parcel, or Rsbuild, and then selecting a Router and other tools ourselves. The React documentation has a direct guide for building a React App from scratch using this approach. It explains that a Build Tool will help package and run the source code, providing a Development Server and a Build Command for deploying the app.  

This approach might be suitable for cases such as:  

• Wanting to add React to only a portion of an existing website.  

• The project has a specific architecture.  

• It is an internal app with a relatively simple scope.  

• The team wants to choose the Data Layer and Router themselves.  

• Wanting to learn how each part of a React App connects together.  

What needs to be watched out for is that as the project grows, the team might have to start managing routing, data fetching, code splitting, error handling, and various conventions on their own more and more. Some teams start this way because they don't want to use a Framework, but eventually end up creating numerous internal conventions until they inadvertently build their own mini-framework.

Then, what kind of project is suited for a Framework?

A Framework is usually suited for apps that have multiple moving parts working together and require a clear structure from the start, such as:

• Having multiple routing pages.

• Loading and mutating data from a Server.

• Requiring Server-side or Static Rendering.

• Having multiple team members.

• Needing shared conventions for everyone to use.

• Not wanting to configure the build and integration for every single part themselves.

React recommends that most new projects will benefit from a Framework, especially when the app requires routing, because a Framework can integrate routing with data fetching and code splitting much more readily than assembling everything from scratch. However, this doesn't mean you must immediately choose it just because you see the word "Framework".

We still need to consider if that Framework:

• Supports the requirements of the project.

• Can be deployed in our desired environment.

• Matches the team's knowledge and experience.

• Actually reduces work through its conventions, or if it adds complexity.

• Provides capabilities that the project truly needs to use.

A popular Framework might be a good choice, but it is not necessarily the most suitable choice for every project.

So, should we still use Create React App?

Currently, Create React App has been declared Deprecated for building new apps. The React team recommends that new projects choose a suitable Framework, or start with a Build Tool like Vite, Parcel, or Rsbuild if you want to assemble the system yourself. If we encounter old tutorials that use the command:

Bash

npx create-react-app my-app

It doesn't mean the React concepts in that tutorial are all wrong, but we should know that this project setup process is no longer the primary approach recommended by the React team today. For new projects, you should always check the latest documentation before choosing a Starter or a project creation command.

FAQ

Is React a Library or a Framework?

React is a library for building user interfaces, according to the description on its official website. It lets us build UIs from components and assemble them into pages and apps. React does not provide a built-in routing and data fetching system for the entire app. If we want to build a full-fledged app, we can use React alongside a Framework, or choose to assemble the other tool parts ourselves.

Is Vite a Framework?

Vite is a Build Tool, not an Application Framework. Its main duty is to help run the source code during development (providing a Development Server) and generate a production build for deployment. Vite can be used with React, Vue, Svelte, and other technologies, but it does not dictate routing or the complete architecture of the app for us.

Can Next.js be used instead of React?

They are not direct substitutes. Next.js is a Framework that uses React Components as the foundation for building user interfaces, and then adds other systems like routing, rendering, and lower-level tool configurations. In other words, when you write Next.js, you are still writing React, but you are doing so under the structure and conventions of Next.js.

Should a new project use Vite or Next.js?

It depends on the nature of the project. Vite is suitable when we want to start from a Build Tool and select the router, data layer, and architecture ourselves. Next.js is suitable when the project needs a Framework that has routing, rendering, and various conventions already prepared. The React team recommends that most new projects consider a Framework, especially apps that require routing, but they still support the approach of building a React app from scratch using a Build Tool like Vite when a Framework isn't suited to the job's requirements.

Conclusion: How do Tools, Libraries, and Frameworks differ?

You can remember it simply like this: Tool helps with certain tasks in the development process, such as building, linting, testing, or managing packages. Library provides APIs or capabilities that we choose to call in our code, like React, which is used to build user interfaces from components. Framework provides capabilities, structure, and conventions, requiring us to write code within its flow, like Next.js. However, these terms aren't always mutually exclusive boxes. Some technologies can support multiple roles, like React Router, which can be used as anything from a declarative router up to Framework mode. Therefore, the important thing isn't just remembering what each one is called, but looking at: Which part does it take responsibility for? How much does it dictate the structure of the project? What matters does it handle for us? What does the team still have to choose and manage themselves?

Because ultimately, choosing a technology is not measured by which one is bigger or has more features, but rather by looking at whether the level of control and assistance it provides is suitable for our project or not.