When it comes to modern web development and data exchange, JSON files have become an integral part in becoming the gateway for these systems. Short for JavaScript Object Notation, JSON is a lightweight data-interchange format that is easy to read and write for us humans, and simple for machines to parse and generate.
In this article, let’s break down what JSON files are, what they look like, and how you can use them in your projects.
What is a JSON file?
A JSON file may look complex at first, but its structure is easy to understand.
Essentially, a JSON file is a plain text file that contains data formatted in its own syntax. It uses the .json file extension and is designed this way so that the software it was made for can access and use the data easily. In this format, the keys act as labels or identifiers, while the values hold the actual data associated with each key.
The syntax of JSON is directly inspired by JavaScript object notation. Its basic rules include:
- Data is written in key/value pairs
- Pairs are separated by commas
- Curly braces
{}define objects - Square brackets
[]define arrays
Additionally, the JSON syntax comes with a set of rules that developers must follow while coding in order for it to work. For example, all keys should be strings wrapped in double quotes, and the values should be written along with one of the supported data types below:
- String
- Number
- Object
- Array
- Boolean
- Null
While some of these data types aren’t usually strings, they still need to be written in a way that follows JSON’s formatting rules. In order to understand this better, let’s see how the data is structured inside a JSON file below.
Why is JSON popular with developers?
There’s a reason JSON has become the go-to format for developers everywhere: it simplifies development workflows.
First off, it’s human-readable. You don’t need to be a seasoned engineer to glance at a JSON file and understand what’s going on. The clean syntax, with its key-value pairs and lack of extra tags or noise, is simple and intuitive.
Second, JSON is incredibly lightweight. Unlike some other formats, there’s no extra overhead. It’s just the data you need, nothing more, nothing less. That makes it fast to transmit, especially over networks where performance matters.
Third, it plays well with many programming languages — not just JavaScript. Whether you’re using Python, Ruby, Java, or Go, chances are your tools already support JSON out of the box.
And finally, JSON is a natural fit for modern APIs. Most RESTful services use it as their default format, which makes integration between apps and services work well. If you’re working in web or app development today, knowing JSON is practically a must.
What does a JSON file look like?
Compared to other formats out there, the JSON file is actually straightforward. It’s built on a simple structure of key-value pairs, which makes the data both easy to read and easy to work with.
Here’s how you can distinguish what a JSON file is:
String
Strings are one of the most basic data types in JSON. They’re always wrapped in double quotes as well as the keys.
| { “name”: “Piper” } |
|---|
Number
Unlike strings, numbers don’t need quotes. You can type in whole numbers or decimals (AKA floating-point numbers).
| { “age”: 22, “height”: 5.6 } |
|---|
Object
An object groups multiple key-value pairs together and are enclosed in curly braces. Each key in the object would still follow the same syntax rules.
| { “employee”: { “name”: “Piper”, “age”: 22, “city”: “Durham” } } |
|---|
Array
Arrays are ordered lists of values and are enclosed in square brackets. They can hold strings, numbers, objects, or even other arrays.
| { “employees”: [“Piper”, “Saxon”, “Lochlan”] } |
|---|
Boolean
Booleans are easy to remember, they’re just simple true/false values, commonly used for things like settings, permissions, or status indicators.
| { “isSubscribed”: true } |
|---|
Null
Null is used when a key exists but doesn’t have a value. Think of it as a placeholder that tells the system, “this is empty on purpose.”
| { “middleName”: null } |
|---|
What are JSON files used for?
JSON files are widely used across many areas of software development. They’re a common way for developers to store and work with data because they’re easy to read and easy to use. Originally, JSON was based on JavaScript object syntax, but over time, it’s become a standard format that works with tons of programming languages, not just JavaScript.
The main thing JSON is used for is moving data between systems. For example, when a website pulls info from a server (your profile, a list of products, or recent messages) that data often comes in JSON format.
But JSON can be used in other things besides websites. It’s also used in mobile apps, desktop software, and even things like smart devices. Basically, if you’re working with software in any form, JSON is probably playing a role behind the scenes.
Top 5 use cases for JSON
JSON is widely used in many software projects. Here are five of the most common ways developers use it:
-
API responses
Most modern web APIs send and receive data in JSON format. When your app fetches user data or a product list from a server, JSON is usually what’s coming back. -
Configuration files
Apps and frameworks often use .json files to store config data. Think of things like package.json in Node.js projects — it defines dependencies, scripts, and metadata all in JSON. -
Storing data locally
Web apps use JSON to save data in local storage or session storage. It helps persist user settings or session info without needing a server call every time. -
Database storage (NoSQL)
Databases like MongoDB store records in a JSON-like format. This makes it super easy to work with if you’re already using JSON in your app logic. -
Data interchange between languages
When you’re writing systems that mix languages, like a Python backend and a JavaScript frontend, JSON acts as the common ground they both understand.
How to open JSON files
Opening a JSON file is straightforward. Since JSON is just plain text with a structured format, you don’t need any fancy software to open it. In fact, almost any basic text editor will do the trick. Let’s take a closer look at the two options that are commonly used to open JSON files.
Windows Notepad or editor
If you’re using Windows, then Notepad is arguably the most straightforward tool to open a JSON file. It comes pre-installed, so there’s nothing to download, and it does the job just fine. Since JSON is text-based, Notepad can display it without any issues, you’ll just need to scroll through and read the structure manually. It’s simple, clean, and great for quick edits.
Notepad++
If you find the regular Notepad lacking and want to use something that has a bit more power but still easy to use, Notepad++ is a great step up. It’s lightweight, fast, and offers handy features like syntax highlighting, which makes reading and editing JSON way easier. Built in C++, it runs smoothly and is especially useful if you’re working with multiple files or digging into more complex JSON structures.
The difference between JSON and JSON files
It’s easy to mix up JSON and JSON files, but there’s a small difference between the two. JSON refers to the data format itself. It’s a way of organizing information using key-value pairs, arrays, and objects. On the other hand, a JSON file is just a text file that uses this format and has its own extension.
Think of it like this: JSON is the style or structure, while a JSON file is the actual file that stores data using that structure. Since JSON is so readable and lightweight, these files are used all the time in things like app settings, server communication, and transferring data between different systems.
JSON vs. HTML vs. XML
While they may all deal with data and structure in some way, JSON, HTML, and XML serve different purposes and have unique strengths.
HTML (HyperText Markup Language) is designed for displaying data — it’s the backbone of how web pages are structured. Think of HTML as the “what you see” part of a website.
XML (eXtensible Markup Language), on the other hand, is more like JSON in that it’s used to store and transport data. But XML is more verbose — it uses opening and closing tags, which can make files bulky and harder to read. XML does offer strong support for complex document structures, though, which is why it’s still used in some legacy systems and enterprise applications.
JSON, meanwhile, focuses purely on simplicity and readability. It doesn’t need all the extra tags XML uses, which makes it lighter and faster to parse. And unlike HTML, JSON isn’t for display — it’s strictly about data.
In short:
- Use HTML when building page layouts.
- Use XML when working with systems that need detailed data validation and structure.
- Use JSON when you want fast, easy-to-read, modern data exchange.
Final thoughts
JSON may seem technical at first, especially if you’re still familiarizing yourself with it. Once you understand the basics, it’s actually pretty simple.
It’s just a clean, organized way to handle data, and that’s why it’s used pretty much everywhere in software development today. If you’re just getting started, try opening up a few .json files with a text editor and experiment with it. It’s a helpful way for you to get familiar with the format and see how different programs use it behind the scenes.
Get started with JSON files on Netlify
When you’re working on a project, whether it’s a website, an app, or anything in between, JSON makes handling data simple and efficient. And Netlify helps developers deploy these projects by automating builds, automating configuration, and connecting APIs.
You can easily integrate JSON files for things like configuration, storing data, or communicating with APIs. Start building with JSON in your projects today and see how it simplifies your workflow.
FAQs about JSON files
Is a JSON file just a text file?
Yes. A JSON file is basically just a plain text file that uses a specific format to store data. You can open it with any regular text editor and you’ll see all the structured data laid out using key-value pairs, brackets, and braces. It’s readable, easy to edit, and super flexible.
Is a JSON file XML?
No, JSON and XML are different file formats used for storing and transferring data. JSON is simpler and easier to read, while XML uses tags and can get a bit bulky. These days, a lot of developers prefer JSON since it’s quicker to work with and cleaner to look at.
Is a JSON file Safe?
For the most part, yes, a JSON file on its own is just text. That said, like any file, it depends on where it’s coming from and how it’s being used. If a JSON file is being loaded into a program or used on a website, it’s important to make sure it’s from a trusted source. But generally, JSON files themselves don’t carry any harmful code.
Why should I use a JSON file?
JSON files are a great way to store and share data because of how simple, lightweight, and easy to understand they are. JSON makes it easy to organize your data and move it between different parts of your system, regardless of the size of your project. Plus, since it works with so many programming languages, it’s super versatile.