Simple Invoice System in PHP with Source Code

A simple project based on Invoice System that uses PHP Language. Following PHP project contains the least but important features which can be in use for the first-year IT students for their college projects. It has a number of important features that will allow all the users to manage their billing with invoices. This system as well as the web application’s concept is all clear, it’s the same as real-life scenarios and well-implemented on it. To download free simple invoice system project in PHP MySQL with source code files, please scroll down to the bottom of this post for the Download button.

About Invoice System PHP Project

Moving on, this simple invoice management system project in PHP focuses mainly on dealing with numerous billing records. Also, the system displays all the available invoice records of each company. In addition, the system allows generating invoices in PDF format. There only a user panel in this simple project. In an overview of this web application, the user can proceed with billing management. For this, the user has to enter the company’s name, address, item name, and quantity. After setting up these pieces of information, the user can proceed towards managing items. Here, it contains a number of fields such as item name, quantity, rate, and tax percentage. Then, the system automatically calculates the total bill of the customer and he/she has to enter the received amount with dues.

Invoice Management

After setting up all the transactions, the user can generate invoices in PDF format. The invoice consists of all the information. Such as invoice number, cashier’s detail, company details, product details with billings. Besides, the user can delete and update available invoices. The main motive of this whole simple project is to generate invoices for each billing. Each user can receive their particular transaction’s invoices. Also, the system lists out all the transactions details with its date and customer’s name with it. For generating invoice bills, the system uses dompdf.

Last but not least, a clean and simple dashboard is presented with simple color combinations for greater user experience while using this Invoicing System Project in PHP MySQL. For its UI elements, a free open-source CSS framework; Bootstrap is on board with some Vanilla CSS too. Presenting a new Simple Invoice Management System in PHP MySQL Project which includes a user panel that contains the least but essential features to follow up, and a knowledgeable resource for learning purposes.

Available Features:
  • List Invoice
  • Manage Billings
  • Generate Invoices in PDF
  • Delete Invoices
  • Update Invoices
Project Name:Simple Invoice System
Language/s Used:PHP
PHP version (Recommended):5.6 or Newer
Type:Web Application
Developer:Vijay Chauhan
Simple Invoice System PHP Project Overview

Instructions: How to Run?

  • After you finish downloading the project, unzip the project file and head over to your XAMPP directory.
  • There you’ll find a folder naming “htdocs”.
  • Inside the “htdocs” folder, paste the project folder (not the .zip one, but the extracted one).
  • Open your favorite browser; we recommend using Google Chrome or Mozilla Firefox.
  • Then, go to URL “http://localhost/phpmyadmin“.
  • Create a Database with a name that is provided inside the “01 LOGIN DETAILS & PROJECT INFO.txt”.
  • Click on the “Import” tab and choose the database file (.sql) which is provided under the folder naming “DATABASE FILE”.
  • After setting up all these, go to URL “http://localhost/[ PROJECT_FOLDER_NAME ]/“
  • All the login details are provided inside the project folder, check that out and enter in order to use it.

And there you have it, a full setup of the Simple Invoice System project in PHP MySQL. For this particular PHP project, PHP Version 5.6 or Newer is required because the project might not operate well with the oldest PHP version. So, users with the oldest PHP version (less than 5.6) might face various problems while operating it. As a result, you’ll need to upgrade your PHP version (only if you’re using the oldest version) at the moment. Download Free Invoice and Billing System Project in PHP MySQL Source Code. So, this invoicing system PHP project is a basic project for all the beginner levels that broads vast knowledge into such PHP web applications. In conclusion, this whole PHP project with free source code is an absolute project and a meaningful way for the users to learn and explore more about it.

Free Download Simple Invoice System Project in PHP MySQL with Source Code:
Click the Download Button Below to Start Downloading

Note: Only for Educational Purpose


  1. Fatal error: Uncaught Dompdf\Exception: file_get_contents(): Passing null to parameter #2 ($use_include_path) of type bool is deprecated 8192 in D:\xampp\htdocs\invoice-system-php\dompdf\src\Helpers.php:507 Stack trace: #0 [internal function]: Dompdf\Helpers::record_warnings(8192, ‘file_get_conten…’, ‘D:\\xampp\\htdocs…’, 839) #1 D:\xampp\htdocs\invoice-system-php\dompdf\src\Helpers.php(839): file_get_contents(‘D:\\xampp\\htdocs…’, NULL, NULL, 0) #2 D:\xampp\htdocs\invoice-system-php\dompdf\src\Css\Stylesheet.php(367): Dompdf\Helpers::getFileContent(‘D:\\xampp\\htdocs…’, NULL) #3 D:\xampp\htdocs\invoice-system-php\dompdf\src\Dompdf.php(572): Dompdf\Css\Stylesheet->load_css_file(‘D:\\xampp\\htdocs…’, 1) #4 D:\xampp\htdocs\invoice-system-php\dompdf\src\Dompdf.php(724): Dompdf\Dompdf->processHtml() #5 D:\xampp\htdocs\invoice-system-php\print_invoice.php(94): Dompdf\Dompdf->render() #6 {main} thrown in D:\xampp\htdocs\invoice-system-php\dompdf\src\Helpers.php on line 507

    1. We’ve been surfing around the internet regarding this issue and found out that this actually occurs with the new PHP ver.8
      In fact, this particular project is targeted and tested with PHP 5.6 and PHP 7

  2. Warning: Use of undefined constant root – assumed ‘root’ (this will throw an Error in a future version of PHP) in C:\laragon……………. on line 136

    Warning: Use of undefined constant invoice_db – assumed ‘invoice_db’ (this will throw an Error in a future version of PHP) in C:\laragon…………… on line 136

    Warning: Use of undefined constant localhost – assumed ‘localhost’ (this will throw an Error in a future version of PHP) in C:\laragon………….. on line 136

    Warning: Use of undefined constant root – assumed ‘root’ (this will throw an Error in a future version of PHP) in C:\laragon………….. on line 136

    Warning: Use of undefined constant invoice_db – assumed ‘invoice_db’ (this will throw an Error in a future version of PHP) in C:\laragon…………………..

  3. Hello sir,
    your system is amazing!
    but i always get this error: 200: undefined while i try to create a new invoice/user.. can you help me?

  4. in page “print_invoice.php?invoice_id=5” error occure this-> 5Unable to stream pdf: headers already sent

    please tell me what i do??

  5. When I am using localhost(xampp server), it’s working. but in online cpanel it shows me an error while printing the invoice ( “6Unable to stream pdf: headers already sent” {here 6 is invoice no. “print_invoice.php?invoice_id=6” } ). it error came from folder ( dompdf/src/Adapter/CPDF.php ). I don’t know why this problem occurred whereas in localhost it’s working.

    1. First off, these projects are clearly targeted at the local host servers. Secondly, we’ve never recommended using these projects in live productions and we can’t allow any of these for live productions. So, sorry we can’t help you with any of these mentioned problems.

  6. HI,

    I got problems to login but I found the files to place the database name, user, and password. (dbcon.php and invoice.php).
    Now I don’t get errors to access the database but at the login page, the system only reloads the page, doesn’t show any error, but does nothing anyway. So, I can’t get the dashboard.

    Can you help me, please?

  7. Hi can you help me, I added an access level of admin, user and guest and so i added new users with different access but when i change to a different access level and user the data is not showing, only in the [email protected] user..thanks. I hope i can get a rely asap..its for my projects:)

Leave a Reply

Your email address will not be published. Required fields are marked *