- Categories API – See below.
- Color Picker API – See below.
- Custom Logo API – See below.
- Dashboard Widgets API
- Database API
- HTTP API
- File Header API
- Filesystem API
- Heartbeat API – See below.
- Metadata API
- Options API
- Pages API – See below.
- Plugin API – See below.
- Quicktags API
- REST API
- Rewrite API
- Settings API
- Shortcode API
- Term Data API – See below.
- Theme Modification API – See below.
- Theme Customization API – See below.
- Transients API
- Widgets API
- XML-RPC WordPress API
Categories API
- Jeremy Heleine. Mastering the WordPress Categories API. sitepoint, 2016.
- Jeremy Heleine. How to List Categories in WordPress Using the Categories API. sitepoint, 2015.
Color Picker API
- Michele Ivani. How to Use WordPress Color Picker API. envatotuts+, 2014.
Custom Logo API
- Jeremy Heleine. How to Use the WordPress Custom Logo API. sitepoint, 2016.
Filesystem API
- Narayan Prusty. An Introduction to the WordPress Filesystem API. sitepoint, 2015.
Heartbeat API
- Tom McFarlin. A Practical Example of the WordPress Heartbeat API. 2014.
- Stephen Harris. Heartbeat API: Using Heartbeat in a Plugin. tutsplus, 2013.
- Pippin Williamson. Using the WordPress Heartbeat API. 2013.
Pages API
- Jeremy Heleine. Understanding WordPress Pages and the Pages API. sitepoint, 2018.
Plugin & Theme API
- Carl Alexander. WordPress for the Adventurous: Plugin API. 2015.
- Great article that helps one understand how the Plugin API works and how to use it. Gets pretty technical, but Alexander is good at explaining complex concepts.
- Stephen Harris. Interacting with WordPress’ Plug-inin & Theme API. tutsplus, 2012.
Quicktags API
- Baris Unver. A Simple Guide to the WordPress Quicktags API. envatotuts+, 2015.
- Recommend this one (oops, for right now it is the only one!).
Screen Options API
- Pippin Williamson. Add Screen Options Tab to Your WordPress Plugin. 2012.
Term Data API
- Tom McFarlin. How to Work with WordPress Term Meta: Term Metadata API. tutsplus, 2016.
- Part of a larger series on term meta.
Theme Modification API
- Tom McFarlin. WordPress Options and Theme Modifications. 2015.
- Explains why we one would use the theme modification API instead of the options API when creating settings for themes.
Theme Customization API
- Narayan Prusty. Getting Started with the WordPress Theme Customization API. sitepoint, 2015.