Theme Check plugin
The WordPress Theme Check plugin for Envato
WordPress options panel for themes and plugins.
A robust code template for creating a standards-compliant WordPress plugin.
WordPress plugin to get updates for themes and plugins from private GitLab repos — can also be implemented into a plugin or theme.
A theme support plugin for WordPlate
WordPress Theme & Plugin management for the Envato Market.
This WP plugin will update GitHub, Bitbucket, GitLab, and Gitea hosted plugins and themes
TGM Plugin Activation is a PHP library that allows you to easily require or recommend plugins for your WordPress themes (and plugins). It allows your users to install, update and even automatically activate plugins in singular or bulk fashion using native WordPress classes, functions and interfaces. You can reference bundled plugins, plugins from the WordPress Plugin Repository or even plugins hosted elsewhere on the internet.