List of Awesome PHP Packages

Symfony Components

Laminas Project (ex-Zend Framework)

Mezzio Framework (ex Zend Expressive): a microframework that heavily uses PSR standards

Aura Project

The League of Extraordinary Packages

PSR-15 HTTP Middlewares: collection of useful middlewares

Paragon Initiative: mostly security related

Spomky-Labs and their minor packages: mostly auth and security

Yii Framework 3: 3.x is not yet released but some packages are quite stable and usable. Look for them in their packagist namespace.

ext-ds: Data Structures, a standard extension worth mentioning. Common data structures like Set, Queue, and Map.

PHP-DI: The best IMHO DI for PHP

fig/http-message-util: HTTP method and status code constants

sabre/dav: WebDAV implementation with CalDAV, CardDAV, etc

sabre/xml: very useful XMLReader / XMLWriter wrapper

yosymfony/toml: TOML parser, unfortunately, outdated

colinodell/json5: JSON5 parser

OpenSpout: Streaming spreadsheet parser and writer (XLSX, ODS, CSV)