Libraries and web tools for developing APIs.

Tools for managing, compressing and minifying website assets.

Libraries for implementing user authentication and authorization.

Project build and automation tools.

Libraries for caching data.

Content Management Systems (CMS),Tools for managing digital content.

Libraries and tools for analysing, parsing and manipulating codebases.

Libraries related to the command line.

Libraries that implement data structure or storage techniques.

Libraries for interacting with databases using object-relational mapping (ORM) or datamapping techniques.

Libraries for working with dates and times.

Libraries and tools for debugging and profiling code.

Libraries that implement the dependency injection design pattern.

Libraries for dependency and package management.

Libraries for project deployment.

Software and tools for creating a sandboxed development environment.

Libraries for generating project documentation.

Libraries and applications for taking payments and building online e-commerce stores.

Libraries for sending and parsing email.

Libraries that are event-driven or implement non-blocking event loops.

Libraries for file manipulation and MIME type detection.

Libraries for filtering and validating data.

Web development frameworks.

Libraries for geocoding addresses and working with latitudes and longitudes.

Libraries for working with HTTP.

Libraries for manipulating images.

Libraries for generating and working with log files.

Libraries for working with markup.

Useful libraries or tools that don't fit in the categories above.

Libraries for working with notification software.

Libraries for working with numbers.

Libraries and software for working with PDF files.

Tools to help install and manage PHP on your computer.

Libraries and software for indexing and performing search queries on data.

Libraries for generating secure random numbers, encrypting data and scanning and testing for vulnerabilities.

Tools for pre-processing content to generate web pages.

Libraries for parsing and manipulating strings.

Libraries for automating and running tasks.

Libraries and tools for templating and lexing.

Libraries for testing codebases and generating test data.

Libraries for accessing third party APIs.