List of useful PHP classes and libraries

Swift mailer
Swift Mailer integrates easily into any PHP application. This is a flexible and elegant OOP approach to sending emails with many functions: sending email using SMTP, SendMail, Postfix, server support, etc.
Phpmailer
The best class to work with email. by mail. Supports messages in digital form, S / MIME encryption, text and HTML letters, images, supports multiple Emails, SMTP authentication.

Securimage PHP Captcha
Script for creating complex images (captchas) to protect against spammers. Easily added to any form.
phpObjectForms
OOP library for creating and processing HTML forms. Key features: support for all standard input forms, server-side checking using regular expressions, client-side checking using Javascript, supports form templates. Forms styles are written in CSS and you can easily customize their display.

PHP Thumb
Small library for working with images: resizing, rotation, Crop. You can also add custom functions. It can perform several actions in succession, without needing to save and reinitialize the class with all the manipulations.
WideImage
OOP library for working with images. It provides an easy way to upload and store images from files, databases and URLs. Supports the most common graphic formats: GIF, PNG, JPEG, GD and GD2.
Smart Image Resizer
Allows you to resize and sprinkle any images on your site without actually touching them. Simply upload images at its maximum size and then use any of its parts. It has many useful features.
class.upload.php
This is a small PHP script for uploading and managing images on the server. It can convert images from one format to another, resize, add labels, watermarks and blur images. You can use it for files uploaded with the help of an HTML form, a flash uploader or local files.
getID3 ()
A PHP script that extracts useful information from MP3 and other multimedia formats (OGG, WMA, WMV, ASF, WAV, AVI, AAC, VQF, FLAC, MusePack, Real, QuickTime, Monkey's audio, MIDI, etc.)

PHPLiveX
A small library that allows you to easily integrate AJAX technology into your web project. You can send form data and send a request to another page without reloading the current one.
Xajax
A very well-known library and Javascript engine that allows you to easily create powerful Ajax applications using HTML, CSS, Javascript, PHP. Pages can asynchronously send requests to the server and update the page content without reloading it.

Simplepie
PHP class that provides a simple API for doing all the dirty work of getting, caching, parsing and normalizing the structure of RSS and Atom formats.

PHP Intrusion Detection System (PHPIDS)
Prevents intruders from trying to disrupt your site. Currently PHPIDS detects all sorts of XSS, SQL injections, RFE / LFI, DoS and LDAP attacks.

ADOdb
Object Oriented Library. Made according to Microsoft's ADO, but has a number of improvements that make it unique (for example, pivot tables, record caching ...). It supports a large number of databases, including: MySQL, PostgreSQL, Interbase, Firebird, Informix, Oracle, MS SQL, FoxPro , Access, ADO, Sybase, FrontBase, DB2, SAP DB, SQLite, Netezza, LDAP.
Doctrine
Represents an object-relational mapping (ORM) in PHP 5.2.3+. The key feature of this library is that it allows you to write database queries in an object-oriented form using your own SQL dialect - Doctrine Query Language (DQL). This is a powerful alternative to regular SQL queries.
PHPLINQ
A set of PHP classes for managing databases.

TCPDF
Class generating PDF documents. Does not require other libraries, supports ISO formats, incl. UTF-8, Unicode, RTL and HTML.
PHPPowerPoint
Works on the basis of Microsoft OpenXML standards. Allows you to read and write PowerPoint documents. Makes it possible to manage meta data (author, title, description, ...), add slides and images to presentations, and more.
PHPExcel
Also works on Microsoft OpenXML. Allows you to read and write Excel files. Features include: editing meta data (author, title, description, ...), managing spreadsheets, fonts, styles, adding images and more.
Phprtf lite
Allows you to create and edit compatible with MS Word and Open Office Writer, RTF using PHP. Allows you to control almost everything. Compatible with UTF-8 encoding.

Source: https://habr.com/ru/post/70808/