Piwigo plugin development documentation, available on the Piwigo website, helps you to start developing your own plugins. The documentation is not extensive, but enough to get you started when you have a background in programming languages. A good knowledge of the PHP programming helps, but to be honest I did not have and managed to write simple plugins. It was my first experience with PHP.

1. Plugin development
   General information about the Piwigo plugin architecture and do’s and don’ts.
2. Plugin tutorial ‘Hello world!’
   General recommendations and how to start writing a plugin. Contains also info about actions and events. 
3. Plugin Tutorial: Several tricks from the Copyrights plugin
   More detailed insight in plugin writing and actions & events. Also touches briefly Smarty, which together with templates is used to generate and layout the webpages.
4. Coding guidelines
   Guidelines how to write your plugin code; naming conventions, code layout, boolean operators to use, quoting of strings, use of comments etc.

It is recommended to use a Source Code Manager (SCM) to have control on your source code and releases. Also information provided how to add the plugin to the translation platform, so other users can provide translations in their language. See also Migrate a plugin from Piwigo.org SVN to Github.

When the plugin is ready you can make it available to other users via the Piwigo extension repository. The development documentation provides instructions how to publish the plugin.