Plugins extend the core functionality of JetBrains products. They provide various integrations (e.g., with a VCS or application servers), add support for different development technologies, frameworks and programming languages, and so on.
The Marketplace (AKA Plugins Repository) is a service responsible for:
Providing a product (e.g., IntelliJ IDEA and other IntelliJ IDEA-based IDEs) with a list of compatible plugins and their updates.
Facilitating the download of compatible plugin updates.
Storage, uploading, and management of the plugins and their updates developed and published by third-party vendors or JetBrains.
JetBrains provides an official plugins repository plugins.jetbrains.com for all IntelliJ Platform-based IDEs, as well as TeamCity, .NET, and Hub (with widgets support for YouTrack and Upsource.) It will be supporting JetBrains Space soon.
This documentation section includes articles, FAQs, and tutorials on JetBrains Marketplace / Plugins Repository operations.
You can always reach out to the plugin repository team via email firstname.lastname@example.org.