In this tutorial we will create a 
Insert Data To JSON File using PHP. This code can insert data to JSON file when user submit the form input. The code use PHP 
POST method to call a function that insert the form data as a JSON object to JSON file using 
file_put_contents(). This is a user-friendly kind of program feel free to modify it.
We will be using 
JSON as a data management to store user data, and it will act as a database storage. It is an open-standard file format that uses human-readable text to transmit data objects into the local server.
Getting Started:
First you have to download & install XAMPP or any local server that run PHP scripts. Here's the link for XAMPP server 
https://www.apachefriends.org/index.html.
And, this is the link for the bootstrap that i used for the layout design 
https://getbootstrap.com/.
Creating The Interface
This is where we will create a simple form for our application. To create the forms simply copy and write it into your text editor, then save it as 
index.php.
- <!DOCTYPE html> 
- <html lang="en"> 
-         <head> 
-                 <meta charset="UTF-8" name="viewport" content="width=device-width, initial-scale=1" /> 
-                 <link rel="stylesheet" type="text/css" href="css/bootstrap.css"> 
-         </head> 
- <body> 
-         <nav class="navbar navbar-default"> 
-                 <div class="container-fluid"> 
-                         <a class="navbar-brand" href="https://sourcecodester.com">Sourcecodester</a> 
-                 </div> 
-         </nav> 
-         <div class="col-md-3"></div> 
-         <div class="col-md-6 well"> 
-                 <h3 class="text-primary">PHP - Insert Data To JSON File</h3> 
-                 <hr style="border-top:1px dotted #ccc;"/> 
-                 <div class="col-md-4"> 
-                         <form method="POST" action="insert.php"> 
-                                 <div class="form-group"> 
-                                         <label>Firstname</label> 
-                                         <input type="text" class="form-control" name="firstname" required="required"/> 
-                                 </div> 
-                                 <div class="form-group"> 
-                                         <label>Lastname</label> 
-                                         <input type="text" class="form-control" name="lastname" required="required"/> 
-                                 </div> 
-                                 <div class="form-group"> 
-                                         <label>Address</label> 
-                                         <input type="text" class="form-control" name="address" required="required"/> 
-                                 </div> 
-                                 <center><button class="btn btn-primary" name="insert">Insert</button></center> 
-                         </form> 
-                 </div>   
-                 <div class="col-md-8"> 
-                         <table class="table table-bordered table-striped"> 
-                                 <thead class="alert-info"> 
-                                         <th>Firstname</th> 
-                                         <th>Lastname</th> 
-                                         <th>Address</th> 
-                                 </thead> 
-                                 <tbody> 
-                                         <?php 
-                                                 foreach($data as $fetch){ 
-                                         ?> 
-                                                 <tr> 
-                                                         <td><?php echo $fetch->firstname?></td> 
-                                                         <td><?php echo $fetch->lastname?></td> 
-                                                         <td><?php echo $fetch->address?></td> 
-                                                 </tr> 
-                                         <?php 
-                                                 } 
-                                         ?> 
-                                 </tbody> 
-                         </table> 
-                 </div>   
-         </div> 
- </body> 
- </html> 
Creating the Main Function
This code contains the main function of the application. This code will insert a  data to JSON file when the button is clicked. To make this just copy and write these block of codes below inside the text editor, then save it as shown below.
members.json
[
    {
        "firstname": "John",
        "lastname": "Smith",
        "address": "New York"
    },
    {
        "firstname": "Claire",
        "lastname": "Temple",
        "address": "Racoon City"
    }
]
insert.php
- <?php 
-         if(isset($_POST['insert'])){ 
-                  
-                         'firstname' => $_POST['firstname'], 
-                         'lastname' => $_POST['lastname'], 
-                         'address' => $_POST['address'] 
-                 ); 
-          
-                 $json[] = $array; 
-          
-         } 
-          
-          
- ?> 
There you have it we successfully created 
Insert Data To JSON File using PHP. I hope that this simple tutorial help you to what you are looking for. For more updates and tutorials just kindly visit this site. Enjoy Coding!