What Is Localhost? A Beginner’s Guide to Local Development and Testing

The first time I developed a website, I published it on the internet under a domain name, even when I was still adding pages and editing content. It wasn’t a huge deal back then, considering my blog had zero traffic, but that’s definitely a no-no for the vast majority of websites in development.

The right solution, which I now implement whenever developing a website, is to use what’s called localhost.

Localhost is how any device or website on a network refers to itself, using an IP address as its local name.

Localhost, in terms of physical devices, applies to the networking name given to a single device running a service or application. For web design, developers use localhost IP addresses to test out websites in a browser — like a temporary domain name — long before making the site live with a real domain name.

As an example, if the localhost of my website is 127.0.0.1, I could type that into my browser (or type “localhost” into the browser) to bring up my development website.

I like to think of localhost as my private website sandbox experience, and I’m here to tell you all about how to use it.

To begin, you must think of localhost as how your device refers to itself on a network. This is its local name, like a nametag to introduce itself to other devices and services on the network.

But that’s mainly how localhost applies to physical devices. Your smartphone, tablet, and computer all have unique IP addresses assigned to them. Those are their localhost numbers.

A web developer, on the other hand, uses localhost in a different way.

Us web developers can save a website’s files on a computer, then use that computer’s localhost IP address to access the website locally.

When you type that IP address, or the word “localhost,” into your browser, the browser sends a query to your computer, so the files get delivered for you to view.

To get you started, here are some useful facts about localhost in terms of development:

• The localhost name assigned to a development website also refers to the physical device you’re using at the time.
• Because of this, typing “localhost” into the browser functions as a loopback address, sending traffic back to your current device.
• The localhost address for virtually every website is 127.0.0.1 (IPv4) or ::1 (IPv6).

I prefer using localhost for every website I develop, even the ones that don’t have any traffic yet.

It keeps everything in an isolated chamber (my device) and ensures my testing environment remains untouched by the internet. And it’s a quick way to load your test website without signing up for a hosting account.

To access localhost, you first open a browser. Then you type “localhost” into the URL bar and click Enter. That process essentially says, “Hey! I want to talk to the computer and no one else.”

Usually, a browser searches the internet, but with localhost, it sends nothing to the internet and, instead, lets you communicate with the device itself.

We call this a “loopback.” The traffic you send through a loopback never leaves your device. It stays on the computer and prompts the computer to potentially dig around in its files.

However, localhost is a very generic way of contacting your computer. There are lots of files on your machine, so saying that you’d like to chat with the computer doesn’t tell it which files you’d like to load. That’s where ports come into play.

• Port 80: Works for locating unsecured HTTP traffic.
• Port 443: Best for bringing up secure HTTP traffic.
• Port 3000: The main port you’ll use to find your local development website, particularly when accessing website files written in certain codes like Node.js or Ruby on Rails.

So, let’s say I’m developing a website locally. I’d need to type http://localhost:3000 into the browser to locate the files holding my website. And here’s the real beauty of localhost: I never need an internet connection to develop a website.

Localhost has many use cases. I mainly use it for web development, but I’ve also found it very helpful for things like debugging and API development.

I’ve mentioned how localhost allows you to skip a hosting account when developing a website. But what’s the point of using localhost when remote servers (those you can get with web hosting) are so readily available?

One point is that remote servers cost money. I’d argue, however, that you need them both, like having a workshop and showroom as a carpenter. Here’s why:

Speed and Accessibility

Localhost is the fastest way to develop a website. Everything happens right on the computer, so you don’t have to sign up for a remote server or wait for the server to reply when you refresh your browser.

Simply put, your request doesn’t travel across the internet when you’re using localhost.

That speed and accessibility make localhost a must-have when developing a website. It provides a rapid development experience for changing code, uploading files, and refreshing the view of your website.

A remote server works great for presenting to clients or publishing a website but, like I said before, it’s better off as a showroom than a workshop.

Security

You can’t beat the security of your local device. I love localhost because I know even an unsecure website isn’t vulnerable to outside forces on the internet. Sure, someone could walk into my office and mess with my local files, but that’s unlikely.

Localhost isolates your entire project from external threats. This is useful for testing features that handle sensitive data, like if you need to test out an eCommerce checkout or databasing feature.

Differences in Environment

Keep in mind, localhost may not provide an exact duplicate of your website when you put it on a live server.

Some features might work differently once it’s launched on a remote server.

I often have trouble with media elements appearing in the same way on a live server as they did in my local environment.

It’s wise to prepare for differences because the PHP version of your localhost configuration will most likely differ from that of the live server. It’s inevitable, so checking your work after making a site live is essential.

I understand it sounds intimidating to set up a localhost environment for the first time. I found it daunting, but I can say that it’s much easier than I expected, and I’m glad I learned how to do it.

Once you learn the steps once, you’ll hardly need to think about how to do it again. Below, I’ll explain the process.

Using Local Servers

My recommendation for beginners is to use a local server stack when configuring localhost on your computer. These stacks are bundles of software that provide everything you need to operate a web server on your computer.

Here are my favorites, all of which include Apache, MySQL, and PHP (AMP):

• MAMP: A Mac-specific PHP development server.
• WAMP: A Windows-specific PHP development server.
• XAMPP: My go-to for use on almost any operating system. It’s a PHP development server which includes Perl alongside PHP.

To configure one of these server stacks, you simply go to their website and download the stack to your computer. Then run the installer and start the server. I’ve found that each of these server stacks comes neatly organized and ready to go out of the box, even for beginners.

Running Servers via the Command Line

For those more daring, or those simply trying to learn something, you have the option to run a local server via the command line on your machine. I’ve used Python’s HTTP server and Node.js in the past, but I find Node.js the simplest.

To start with, Node.js:

1. Create a file called server.js. Save it to your computer.
2. Put the following code in that file and save the file again:

const http = require('http');

const server = http.createServer((req, res) => {

  res.writeHead(200, {'Content-Type': 'text/plain'});

  res.end('Hello World!');

});

server.listen(3000, 'localhost', () => {

  console.log('Server running at http://localhost:3000/');

});

With the file saved, you’ll open the command line on your computer and run this command: node server.js. That starts a web server running in the background of your computer as localhost.

Accessing Your Application

Now that we have the local server running, you’ll want to access your application. Luckily, all that’s required is to open your web browser.

Here are the steps:

1. Open your browser.
2. Type in this address http://localhost, or http://localhost:3000 if you’re using a specific port as discussed before.
3. You should now be able to view the application in the browser.

Remember, you can also use the localhost IP address instead of http://localhost. That’s usually 127.0.0.1, but you have the option to change it.

You’ll encounter a wide range of ports when using localhost for web development. Think of these ports like channels on your television.

They allow different services to run on the same device, but they run independently when chosen. So, you can run a development website without touching another application on the same device.

• Default Ports: The default ports are usually associated with specific applications. For instance, port 80 is common for web servers, while port 3306 is known for MySQL. Port 443 always handles secure applications, and port 3000 is the usual choice for development applications.
• Custom Ports: You can technically specify any custom port you want, especially if your desired port is already in use. A great example is port 8080, a custom alternative to port 80 when it’s already in use.

It’s important to remember that you can use any port you want. These are just standards. I recommend sticking to the standards since they’re easy to remember after you’ve used them a few times. Yet, you can always use any port you like as long as it’s open.

I’ve portrayed localhost as this beautiful, seamless tool for developing a website in an isolated environment. But creating a localhost system and running it doesn’t always go as smoothly as I’ve made out.

You will most likely encounter some roadblocks. The best course of action, though, is to learn from my mistakes to prepare for these potential issues.

Port Conflicts

The issue I’ve encountered the most with localhost is what’s called a port conflict. It occurs when you try to use a server port that’s already taken.

It’s like trying to claim an in-use phone number as your own. You just can’t do it.

The good news is that you’ll usually receive an error message telling you about the port conflict. That message reads like “Port is already in use” or “This address is already in binding.”

To resolve the issue, here’s what I recommend:

1. Close all the applications you suspect of using the port.
2. If that fails, use a command on Windows or Mac to identify the application using the port. On Windows, it’s the netstat -ano | findstr : command. On Mac, it’s the lsof -i : command.

As an alternative, you can create a custom port for the new application. That’s especially true if there’s another important application on the current port.

Access Denied Errors

The “Access Denied” error tells me there’s something up with my permissions. Most likely, my computer doesn’t allow the server to read or write the file I’m trying to bring up in my browser.

To fix this error:

1. Make sure you’re running the development environment as an admin on Windows.
2. On Mac, consider using the sudo command for an administrative environment.
3. Check to see if your project files have the right permissions.
4. Check to see if the user account on your computer has read and write access to your files.

There’s nothing else going on with an “Access Denied” error. Whenever I’ve seen it, the error has something to do with permissions. Switching to an administrative position almost always fixes the problem.

Firewall or Security Software Blocks

I’ve rarely stumbled upon a situation where my firewall settings block localhost. To check for this issue, open the firewall settings on your computer to see if it allows for connections to localhost.

Alternatively, you can turn off your security software or firewall to see if the problem goes away. Just be sure to re-enable it when you’re done.

After countless hours developing websites with localhost, I’ve made enough mistakes to gather some best practices to help you avoid my blunders. Here are my favorite tips to guide you along the way:

Keep Your Environment Updated

I keep my phone updated. I keep my computer updated. I even keep the software on my smart TV updated. It’s all for security, so why wouldn’t I update the environment for my local server?

You’ll want to update everything from your programming languages to the web server. This way, your sandboxing tools stay in the best condition, they perform well, and you minimize security risks.

Organize Projects and Port Numbers

For a while, I thought port numbers were just a way for my computer to organize how it connected to files, but they’re so much more than that. Eventually, I realized the power of port numbers for my own sanity.

It’s important to use unique ports for each project. To avoid conflicts, at least. But ports also work well for quickly switching between projects.

For instance, I might organize like this:

• Project 1: http://localhost:3000
• Project 2: http://localhost:3010
• Project 3: http://localhost:3020

A structure like that saves me a significant amount of time. That’s because I rarely encounter occupied ports, and I’m able to just write down the ports that correlate with each project to easily find them.

Use Version Control

Version control has saved my butt several times. It tracks my changes and saves old versions for me to revert to if necessary. If I mess up while experimenting with new features, version control lets me jump back to a previous version with the click of a button.

That’s why I recommend using Git, or any version control system like GitLab or GitHub, to log every step of your development process. As a bonus, services like GitLab and GitHub have the option to save off-site backups for added protection.

I’ve used paid sandboxing tools and self-configured ones on remote servers, but none of them offer the simplicity and flexibility as localhost on my own computer.

You can use localhost for anything from APIs to general website building, and it stays accessible even when you lack an internet connection.

I’ve walked you through the ins and outs of localhost. I’ve even explained how to quickly get set up with a localhost stack like WAMP or XAMMP. And believe me, configuring those tools is possible for even the most nervous of beginners.

So, now it’s time to give yourself a gift: a secure, speedy, and isolated sandbox experience with localhost.